Where to get a new exhaust system?


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Like it says I need to get a new exhaust system one that replaces the car, minus all the junk between the car and the muffler, a deeper throatier sound and preferably and exhaust tip coming out of each side. My cat is going bad so I want to replace it all and I must have California emissions cause it looks like I have two cats and two mufflers 😂.
If anyone can give me product numbers and cheapest places to go online I will put you on my Christmas card list 😃. Thanks guys

Can you confirm if this is for your TB, or another vehicle, since you posted in the full size section? Your TB, if the exhaust system is stock, would have a cat, muffler, and resonator... So I'm a little confused about your setup.

The sticker in your glovebox should say if it has CA emissions, which may be one of the RPO codes listed in this document:

The underhood sticker should say if it's a federal or CA emissions.

And as @Blckshdw said. Two converters is usually on V8's.

I just order the muffler and parts needed then hit up a local shop to bend and weld up the pipes between. Always been far cheaper than buying a full aftermarket system and you get to pick your sound a bit more.

When you are ready and know what you need, make sure to compare prices. When I did the exhaust on my Sierra some parts came from Amazon, some from RockAuto, and the most expensive part came from Summit Racing because they were $75 less than others for the same pipe, same brand.

One thing's for sure, Walker mufflers are not recommended as they are necked down internally and thus, lower flow.

I’m sorry I did not notice this was in the full size forum, newbie screw up sorry guys.
It is for a trailblazer LSU and the emissions is for all 49 states so not CA emissions just seems like a lot of inline junk.
Anyway I’d like it to sound like a truck and a tip out of each side and I’d honestly like to just get rid of the cat but I couldn’t tell if their were any sensors after it cause I know if there are it won’t work

You won't get that type of sound out of an inline engine, like you would from a V8, the acoustics just don't work out that way. What you may try doing, is search Youtube for Trailblazer aftermarket exhaust videos. When these types of threads would pop up in years past, they would get posted, and you could get an idea of how some brands sounded to get an idea if it was close to what you wanted, or completely missed the mark.

One thing to keep in mind, sounds and looks are all subjective according to each person, so it's likely that something you like, a number of others won't. So it's hard to get an accurate recommendation on "fun mods" like this.

Don't think loosening the bottom will do anything. Probably have to take the strut/spring assembly apart again and re-assemble with the strut centered. I don't remember there being that much play in the upper mount though.

Just looked at mine. Stock mounts are different. They stick up through that big hole. Yours look different.
Probably because I put it together right after taking it apart and splitting my finger open in the process lol. Mine are bilsteins with a leveling kit so I hope that's it, not just something else messed up haha

Did you use new mounts or reuse old?
I'm not knowledgeable with what's what on suspension so I'm gonna try and describe and see if you know. I reused the arm that the strut sits in, reused springs, and the top and bottom cushion looking guides the spring ends line up on, then the top that holds it all is the rough country leveling "puck?" Sorry wasn't sure how else to refer to it


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One thing's for sure, Walker mufflers are not recommended as they are necked down internally and thus, lower flow.
Hijacking the thread for my own selfish needs...

Does this apply just for the 360/370, or for all applications that Walker makes mufflers for?
I've had my muffler order on hold for a bit, but intended on getting a Walker for the Sierra.


I think it might be just 360/370's because they use a funky 2.75" pipe and Walker necks it down to 2.5.


So you could just order a 3 inch walker and slide over? Or is it further necked down internally?

Seems pretty common to slide a 2.5 muffler inside our pipe or a 3 inch over. Never heard that the 2.5 was any less performance over all these years. I would actually say more use 2.5 than 3 on the I6 cause the 2.5 is most common.

I believe my Hooker was a 2.5 and they expanded the inlet to match the 2.75 when they welded it up, but it was a 2.5 exit to a 3.5 tip and it was better than my current 3 inch magnaflow.


The stainless JBA cat-back I got a few years ago was 3". Apart from sounding like a ricer, it flowed very well.

If you think about how much exhaust has to be pumped out a 4.2L, 2.75" is spot on. My son's 4.8L has 3" out the back. My Saab 5.3L also has 3". Engineers finally realized that 2.5" everywhere doesn't work. I remember when that was standard on 350/5.7L small blocks. My Caprice's 6.0L is severely choked at the cats where they neck down to 1 7/8". I guess Holden didn't get the memo. I'm gonna do a before and after dyno when I install my full exhaust system with headers.


Full 2 inch headers and 3 inch exhaust is good for about 40 HP on my LS1; however I really don't think using a better flowing aftermarket 2.5 muffler in place of the the giant restrictive stock 2.75 is going to cause any reduction in performance on the inline 4.2. Probably increase it really.


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Before I started on some motor work, I was thinking about replacing the converter if it was failing and also the resonator.

My plan was either a 2.5" or 3" resonator with a tip. This is what I was looking at.


2.5" resonator

2.5" Inlet, 3" outlet exhaust tip

3" Resonator

3" inlet exhaust tip

If you don't care about being whisper quiet then any 2.75" free flowing muffler should work.

The stock system is fairly free flowing, I measured less than .5 PSI on mine. However it comes down to more than pressure and flow/velocity have to be factored.

I'm no exhaust engineer, but the way I understand it is you want to keep the exhaust flowing smoothly the entire way and when it cools down, it's harder to push through the piping.

I don't think that if you simply added a free flowing muffler and the Vibrant resonator, that you would alter the balance.
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