Kooks 4.2L I6 Header

[rmsg0040]

That sucks big time

 

[Kuchar09]

Well I'v had my header on for about 3 weeks now and have to say I'm happy with how it turned out! I did notice my engine light came on after 50 miles and gave me the code P1133. The engine light then shutoff after 200 miles but the code still shows up in torque so not sure why the light isn't on. I'll have to keep an eye on this till I have an open week where I can send the PCM out for a re-tune.

In order to make this work on my 06 Kooks sent out the adapter show below which worked perfect I just had to run out and get a new gasket.



Here a video of the first time I started it up without the muffler attached.

[video=youtube;ipsmrcjMors]http://www.youtube.com/watch?feature=player_embedded&v=ipsmrcjMors[/video]

 

[dmanns67]

So with the adapter from Kook's, you can use the 02-05 header on 06-09?

 

[Kuchar09]

So with the adapter from Kook's, you can use the 02-05 header on 06-09?

Yup just had to cut off the old flange and clamp the new one on.

 

[Cdrum]

Big to fishsticks. I used the directions to do my first header install. Our much loved '02 Envoy with 75,000 miles on it was starting to feel lethargic, and the exhaust had a sulfur/rotten egg smell to it whenever I towed our boat around. I figured the cat was getting on in age and due for replacement. I knew one exhaust manifold bolt was already broken off, so it seemed wise to just replace the whole manifold and cat. I pretty much followed his directions, with a couple of observations along the way:

• Though I PB Blastered, WD-40'd and whatever I could think of the 3 nuts holding the downpipe to the exhaust manifold were gnarley. This by was the longest part of my install - figure a couple of hours for all 3. I attempted getting the back 2 off from the wheel well using sockets and box wrenches - forget it. You need to get under, get really good purchase with socket, extensions and in my case a 24 inch breaker bar.
• The cat connector pipe to axle back, well I snapped a stud. Drilled it out and bolted it up.
• I had no prayer of getting the transaxle cross member out. The sawsall was my friend freeing the old pipe after cutting it.
• Neither of the O2 extenders that came with Kooks were right. No prayer of getting either of the old O2 sensors out, so I replaced both. Used the old O2 wires and plugs and soldered them onto the new as a extensions. (Some debate if its ok to solder O2 wires, but besides having to get them really hot to flow solder, I haven't had a problem.)
• The rear O2 sensor connector on my '02 is up behind a heat shield. You can neither see it nor reach it with both hands at the same time. A bit tricky to plug the O2 sensor back in one-handed.
• The header bolt closest to the firewall was snapped. I was able to slowly turn it out with vice-grips. I should have chased the threads, but didn't. Upon reinstallation I couldn't get the new bolt to seat all the way - not sure if that bolt hole was just more shallow, or if there was something in there. I backed the bolt out, put another nut on it and retightened it. :fingerscrossed:
• The heat shield directly under the firewall backward interfered with the new header. Bending it out of place dampened the noise down a bit.
• The AC drain hose is directly above the header connection pipe. After driving to work with the AC on, the car sounded like a pressure cooker getting ready to explode. I cut about a 14 inch section of garden hose and was able to interfere fit it into the drain elbow, and reroute the drain past the header, and pinch it between the heat shield and chassis rail.
• Installation of the header bolts was a bit tricky, but going through the wheel well as recommended is really the only way to access the rearmost header bolt, and the best way to reach many of the others. Wobble extensions work great here.

The header appears to be very well made, and fit quite well. The truck seems to run a bit freer, and maybe 5-10% pickup in gas mileage. I made an O2 extender for the rear sensor, and after about 2 1/2 tanks of gas no CEL yet. I've ordered HPTuners, and hope to do a tune in the future, though I might get some help with a remote tune.

It is a bit louder, but mostly just mechanical sounds from the engine bay. I saved the old heat shield from the top of the exhaust manifold - I may try to modify to go back in over the header.

This was my first header install ever. I'm reasonably mechanically inclined, but work with computers and people in the day job. Probably took me about 7-8 hours total. I'm sure those with more talent and access to a torch to free things up could do it quicker.

Oh one more thing, 13mm sockets must be cursed. I've lost a total now of 3 in the Envoy's engine bay -

 

[novajoe]

Big to fishsticks. I used the directions to do my first header install. Our much loved '02 Envoy with 75,000 miles on it was starting to feel lethargic, and the exhaust had a sulfur/rotten egg smell to it whenever I towed our boat around. I figured the cat was getting on in age and due for replacement. I knew one exhaust manifold bolt was already broken off, so it seemed wise to just replace the whole manifold and cat. I pretty much followed his directions, with a couple of observations along the way:

• Though I PB Blastered, WD-40'd and whatever I could think of the 3 nuts holding the downpipe to the exhaust manifold were gnarley. This by was the longest part of my install - figure a couple of hours for all 3. I attempted getting the back 2 off from the wheel well using sockets and box wrenches - forget it. You need to get under, get really good purchase with socket, extensions and in my case a 24 inch breaker bar.
• The cat connector pipe to axle back, well I snapped a stud. Drilled it out and bolted it up.
• I had no prayer of getting the transaxle cross member out. The sawsall was my friend freeing the old pipe after cutting it.
• Neither of the O2 extenders that came with Kooks were right. No prayer of getting either of the old O2 sensors out, so I replaced both. Used the old O2 wires and plugs and soldered them onto the new as a extensions. (Some debate if its ok to solder O2 wires, but besides having to get them really hot to flow solder, I haven't had a problem.)
• The rear O2 sensor connector on my '02 is up behind a heat shield. You can neither see it nor reach it with both hands at the same time. A bit tricky to plug the O2 sensor back in one-handed.
• The header bolt closest to the firewall was snapped. I was able to slowly turn it out with vice-grips. I should have chased the threads, but didn't. Upon reinstallation I couldn't get the new bolt to seat all the way - not sure if that bolt hole was just more shallow, or if there was something in there. I backed the bolt out, put another nut on it and retightened it. :fingerscrossed:
• The heat shield directly under the firewall backward interfered with the new header. Bending it out of place dampened the noise down a bit.
• The AC drain hose is directly above the header connection pipe. After driving to work with the AC on, the car sounded like a pressure cooker getting ready to explode. I cut about a 14 inch section of garden hose and was able to interfere fit it into the drain elbow, and reroute the drain past the header, and pinch it between the heat shield and chassis rail.
• Installation of the header bolts was a bit tricky, but going through the wheel well as recommended is really the only way to access the rearmost header bolt, and the best way to reach many of the others. Wobble extensions work great here.

The header appears to be very well made, and fit quite well. The truck seems to run a bit freer, and maybe 5-10% pickup in gas mileage. I made an O2 extender for the rear sensor, and after about 2 1/2 tanks of gas no CEL yet. I've ordered HPTuners, and hope to do a tune in the future, though I might get some help with a remote tune.

It is a bit louder, but mostly just mechanical sounds from the engine bay. I saved the old heat shield from the top of the exhaust manifold - I may try to modify to go back in over the header.

This was my first header install ever. I'm reasonably mechanically inclined, but work with computers and people in the day job. Probably took me about 7-8 hours total. I'm sure those with more talent and access to a torch to free things up could do it quicker.

Oh one more thing, 13mm sockets must be cursed. I've lost a total now of 3 in the Envoy's engine bay -

I have been extremely happy with the headers on my trailblazer.

 

[Cdrum]

3 weeks now, and between the header and the tune it's driving very well. Oddly, it seems to coast far better than before. Go figure.

 

[XUVFISCH]

I just finished up installing the header. When I was going to connect the cat to the muffler, it was about 10" short.

Any of you guys run into this problem. I have the XUV with the long wheelbase. Do all you guys that installed it have the short wheelbase?

 

[novajoe]

I did not have this problem but mine is not a long wheel base. When you ordered the headers did you tell them it was a long wheel base? I think they make an extension to fix that.

 

[XUVFISCH]

they never asked.

 

[novajoe]

they never asked.

Call them and let them know have the longer wheel base. I know when they were working on mine they were going to make an extension for the longer TB's.

 

[XUVFISCH]

they sent me a extender piece. I got it all done now. What type of tune did you get for yours? anything special or just stock. what shift firmness? and where do you find the Broadcast Code? thanks for your help.

 

[novajoe]

they sent me a extender piece. I got it all done now. What type of tune did you get for yours? anything special or just stock. what shift firmness? and where do you find the Broadcast Code? thanks for your help.

I had a full dyno tune done at PCM for Less. They used my TB to map out a tune that you can order. The tune really complemented the headers and helped free up the motor. The before and after dyno sheet is posted in this thread. Give PCM for Less a call and they can tell you more. Just tell them you talked to the guy that has the prototype truck. The broadcast code is on the sticker attached to the ECM.

 

[marshall@pcm]

We don't need the broadcast code for those vehicles. That's for the older chip stuff(93 and back).

 

[seanpooh]

I finally took the plunge and purchased the headers for the XL. I bought it on the Friday of Labor Day so I got a discount and free shipping. It was the best deal by far that I could find anywhere. The bad thing is that it's a 3 week special order wait. Plus non refundable...

But that just gives me more time to PBblast the bolts. One head of a bolt is already missing...

Marshall @ PCM, if you're reading this; I already purchased a tune from you guys. Now what if I wanted my PCM to have the tune for the new headers, would I have to pay for a whole new tune or how does it work?

 

[HARDTRAILZ]

I paid $50 for a re-tune. I believe the info is on their page.

 

[marshall@pcm]

This^^!!

 

[novajoe]

I finally took the plunge and purchased the headers for the XL. I bought it on the Friday of Labor Day so I got a discount and free shipping. It was the best deal by far that I could find anywhere. The bad thing is that it's a 3 week special order wait. Plus non refundable...

But that just gives me more time to PBblast the bolts. One head of a bolt is already missing...

Marshall @ PCM, if you're reading this; I already purchased a tune from you guys. Now what if I wanted my PCM to have the tune for the new headers, would I have to pay for a whole new tune or how does it work?

SOAK the bolts as much as possible! The bolts are the hardest part of the install!

Marshall I will be seeing you at your shop next week to pick up my E-fan kit!

 

[XUVFISCH]

I finally took the plunge and purchased the headers for the XL. I bought it on the Friday of Labor Day so I got a discount and free shipping. It was the best deal by far that I could find anywhere. The bad thing is that it's a 3 week special order wait. Plus non refundable...

But that just gives me more time to PBblast the bolts. One head of a bolt is already missing...

Marshall @ PCM, if you're reading this; I already purchased a tune from you guys. Now what if I wanted my PCM to have the tune for the new headers, would I have to pay for a whole new tune or how does it work?

Make sure and tell them you have the XL to the extender piece

 

[marshall@pcm]

Marshall I will be seeing you at your shop next week to pick up my E-fan kit!

Sweet!

 

[seanpooh]

I actually didn't get it from PCM cause another speed shop actually has a better deal. Also Kooks makes the headers specifically for the XL so no extender piece needed.

I think I'm going to get the Irwin bolt extractor, it seems to get the job done on them bolts.

 

[XUVFISCH]

I had a mobile mechanic come over for $75 to get my 2 furthest back bolts out. They were broke off before I even pulled the cracked manifold out. He welded a nut on it and got them out in 20 minutes.
All the other bolts came out pretty easy, the front ones were not even that tight. Are you sure they make a 1 piece unit for the XL's? They never said anything about it to me. I'm not to happy about cutting off the end and clamping on the extension piece.

 

[seanpooh]

Yeah, I wish I had a MIG welder and knew how to use it. My dad only has rod welders and aren't too precise. But I guess I shouldn't be too worried. Yeah, one bolt head in the rear is already gone.

As for the XL version, yeah they make that. If you go onto the kooks website, they have the SWB and LWB each has their own model number and again you have the catted, Green and off road versions just like the SWB. The one I got is 6330 which is catted.

This wasn't too long ago either that I noticed the longer headers. I've been looking all year then one day the option popped up for the XL.

 

[HARDTRAILZ]

Different part number, does not mean you wont get the swb version with the extention....

 

[XUVFISCH]

Different part number, does not mean you wont get the swb version with the extention....

I guess we'll see in 3 weeks!!

 

[seanpooh]

Yeah, that's what I was going to say. When I receive it, i'll update you guys and post up pictures.

 

[seanpooh]

So I finally got the headers today, took long enough. It was packed pretty well and is pretty well built.

The end that goes to the muffler, it looks to be like an extender piece but it's integrated it. Let's just hope they got the length right on the XL.

Along with the header and cat, it came with the gasket (which feels like cotton), new bolts and o2 sensor extender cables. Only thing missing, instructions Not that I need them since lots of members here did write ups but still, everything comes with instructions. Regardless, I cannot wait to install it!

Enjoy some pictures.

 

[seanpooh]

Just an update, I finally got the headers in.

They fit perfectly and work well. It makes the engine breath better especially climbing a slight hill where the gear doesn't drop down to increase RPM. I haven't seen an increase or decrease in MPG then again I haven't sent in my PCM for a retune to compensate for the headers.

No more droning in the cabin and the tone is much more mellowed out and deeper. Still not like a V8 though.

Hardest part of the install was getting the heat shield out of the engine bay. I ended up bending it in there and then removing it. I already replace my catalytic converter before so I had put anti-sieze on those three bolt on the manifold. My manifold didn't have a crack in it so it will be up in the sales section along with the Magnaflow catalytic converter.

Just an important note, those bolts on the cylinder head are actually 1/2" socket fit. The 13mm will fit but there is still play, the 1/2" socket fits snug and securely.

Also removing the bolts that had a broken head, I used the Irwin bolt extractors size 5/16"-8mm and it worked like a charm. I had three broken head bolts in the back and all came out without much effort. My heart was actually racing though. Because the three head bolts were broken in the rear, I had an exhaust leak in that last cylinder which could be seen by the carbon the silver stock gasket.

I did have to buy a new downstream O2 sensor since the old one which wasn't that old in age would not budge at all. I spent $30 on a 22mm snap on oxygen sensor socket and all it did was round the edges. Now because of the different O2 sensor locations, the snap on socket won't fit in the locations therefore will be up for sale also.

The write ups here cover pretty much everything there is for the install. If any one has questions about the install I'll be glad to answer questions.

Is it worth the ~$900? Personally, not really. I could of done without it and put the money towards SS rims but once I get the retune my mind might change.

 

[xtitan1]

Just an update, I finally got the headers in.

They fit perfectly and work well. It makes the engine breath better especially climbing a slight hill where the gear doesn't drop down to increase RPM. I haven't seen an increase or decrease in MPG then again I haven't sent in my PCM for a retune to compensate for the headers.

No more droning in the cabin and the tone is much more mellowed out and deeper. Still not like a V8 though.

Hardest part of the install was getting the heat shield out of the engine bay. I ended up bending it in there and then removing it. I already replace my catalytic converter before so I had put anti-sieze on those three bolt on the manifold. My manifold didn't have a crack in it so it will be up in the sales section along with the Magnaflow catalytic converter.

Just an important note, those bolts on the cylinder head are actually 1/2" socket fit. The 13mm will fit but there is still play, the 1/2" socket fits snug and securely.

Also removing the bolts that had a broken head, I used the Irwin bolt extractors size 5/16"-8mm and it worked like a charm. I had three broken head bolts in the back and all came out without much effort. My heart was actually racing though. Because the three head bolts were broken in the rear, I had an exhaust leak in that last cylinder which could be seen by the carbon the silver stock gasket.

I did have to buy a new downstream O2 sensor since the old one which wasn't that old in age would not budge at all. I spent $30 on a 22mm snap on oxygen sensor socket and all it did was round the edges. Now because of the different O2 sensor locations, the snap on socket won't fit in the locations therefore will be up for sale also.

The write ups here cover pretty much everything there is for the install. If any one has questions about the install I'll be glad to answer questions.

Is it worth the ~$900? Personally, not really. I could of done without it and put the money towards SS rims but once I get the retune my mind might change.

I'm taking notes lol. Very impressive you are able to do this stuff on your own. I'm curious to see what you say after a PCM retune!

 

[million-miles]

Just looked at the kooks web site for the price of the headers. HOLY SH** a grand for our headers.

 

[Playsinsnow]

If they were cheaper we would all have them. At what level performance gain would you expect from a cheaper header on a platform not produced anymore. Give me a header, I know it is not going to happen, that has more considerable HP gains than the kooks and I'd consider it. Be a different story if it was a small block v8.

I read one post where he thought it was not worth the $900 he spent. Others rave about it. If I soent a grand, I would be hard pressed to find more reasons to like it than to admit that it was not worth it. Kooks does have a quality rep though...

 

[smokey262]

I understand that they are very nicely made, and a quality product. But that kind of scratch buys a lot of other toys. Besides, its hard for me to forget when SBC headers were like $120

 

[blazinlow89]

If they were cheaper we would all have them. At what level performance gain would you expect from a cheaper header on a platform not produced anymore. Give me a header, I know it is not going to happen, that has more considerable HP gains than the kooks and I'd consider it. Be a different story if it was a small block v8.

I read one post where he thought it was not worth the $900 he spent. Others rave about it. If I soent a grand, I would be hard pressed to find more reasons to like it than to admit that it was not worth it. Kooks does have a quality rep though...

Well everybody and their mother makes a header for the SBC. Of course with us the 4.2 is basically a bastard engine. While it is a great engine (to most of us), the general use of it was very limited. It is also a bit different when you throw bolt ons at a DOHC engine, its not like the engines of the past where a header can add 40-50 HP easily. For the price it is a fair deal considering it replaces a weak point being the factory manifold. As well as give you a few extra ponies. If someone had the time to optimize a tune I think we could see bigger gains. For Kooks and PCM of NC, the R&D that has been done is worthy of the price. Some may see it like me, others may not. However working with custom race products this stuff just does not happen overnight, it takes time, money, man hours, effort etc.

That being said, If still available next year I may pull the trigger and get one as I just started hearing the diesel sound in the AM. Not sure if its cracked or loose hardware, but this would be worth it to replace the OEM one (to me at least). Just not at the current time, planning a wedding.

 

[Playsinsnow]

They did put a lot of R&D into it. I've seen the dyno #s and the improvement is definitely there. Can not justify it for my needs though. Give me the same numbers for my wife's car and maybe... it is definitley worth the scratch to someone else. If I have to replace the header I will consider it. Depends on how many other goodies I can get when time comes to go shopping.

 

[blazinlow89]

They did put a lot of R&D into it. I've seen the dyno #s and the improvement is definitely there. Can not justify it for my needs though. Give me the same numbers for my wife's car and maybe... it is definitley worth the scratch to someone else. If I have to replace the header I will consider it. Depends on how many other goodies I can get when time comes to go shopping.

Of course new header would call for new exhaust, which would all but justify a tune. Then who knows from there.

 

[Sparky]

I understand that they are very nicely made, and a quality product. But that kind of scratch buys a lot of other toys. Besides, its hard for me to forget when SBC headers were like $120

Yeah, but not $120 for stainless steel, including a cat, at low production volumes.

 

[palitoiii]

You guys that have the headers. Update how are they so far? How do you like? Is it worth the coin? Or better off just getting a new exhaust manifold from like rockauto.com?

 

[seanpooh]

I like it, gives more throttle response, sounds better and looks bad ass. I also gotten the tune from PCM where they disabled the CES light and changed timing which improved performance overall but just slightly.

Is it worth the price though... Not to me really. It it was cheaper around $200-$500 then yes. I could of used it towards bills but I did have $725 hanging around and I figured it would be a nice Christmas present to myself.

The money would have been better spent towards a bore and hone of the engine maybe but it's an aftermarket part that improves the engine slightly.

I you plan on getting the headers, make sure to wait for a holiday, get free shipping and request a call from Maryland speed to get the best price.

 

[HARDTRAILZ]

I like it, gives more throttle response, sounds better and looks bad ass. I also gotten the tune from PCM where they disabled the CES light and changed timing which improved performance overall but just slightly.

You may have gotten the throttle response from the tune cause that it one of its biggest benefits.

 

[Cdrum]

I did the header and PCM remote tune at the same time. For me the combination has been well worth it. Since I did both together, tough to say how much is attributable to each. The net effect though has been dramatic- throttle response is better all around, more power in part throttle situations, and shifting is much much improved. Where I noticed it the most was towing our 5000 pound boat+trailer through the mountains of NY - much gutsier pulling up hills than on previous trips.

Couple of cons/neutrals though too:

-AC drain drips onto the header, I had to rig up a drain extension, not big deal until it started cooking on the header pipe. Try #2 involved wiring it to the frame rail (disappointingly redneck solution )

-mileage mostly the same

-high flow cat - wife complains the truck is smelly from a cold start. This could be the tune too.

- o2 extensions that came with the kit weren't right. Used the wires, soldered onto the existing connectors.

I suspected the original cat was bad, and knew I had an exhaust leak at the manifold if not a cracked manifold. So I figured the cost of OE or factory type parts significantly offset the premium of the header and cat.