Does anyone have any recommendations for aftermarket headers? I've had custom exhaust installed on my 08 envoy denali 5.3L and was looking for a exact swap header manufacturer. I've heard that finding headers that swap with stock manifolds can prove to be quite the task?
The 5.3 is pretty much an LS motor just like the 6.0, the engine bay should be near identical in layout to the SS (the front drive shaft appear to be in same spot as the AWD SS). So whatever headers fit the SS should fit the 5.3 with minimal modding/changes.
Without making any recommendation for or against CAT Deletes via Long Tube Headers... These two videos show the difficulties involved ...First from Professional Mechanics using a Shop Lift Involved R&R, while the Second Video shows that TWO People working on a Jack Stand Supported Trailblazer at Ground Level have even more difficulties to overcome. Please note that had the two Dudes in 2nd Video removed both Front Wheels... Their installation procedures would have been a whole lot easier to accomplish:
If your State is CARB Compliant and only the Shorty Headers will do... Shopping Amazon, eBay and even JCWhitney might reveal the Best Price Point versus Header Quality as per Buyer Reviews. Try to find the Highest Quality 304 or better Stainless Steel and look for the Quality and completeness of fully circumferential Pipe Welds to the Thick Flanges. This route may prove a whole lot less laborious as well.
Wear Gloves when handling the Polished Stainless Steel and prior to Turning the Ignition Key, be sure to "Wipe Each Pipe" down with a Good Solvent to remove all of the Oils and Amino Acids left on the S/S from touching the headers with your Bare Hands during installation... or as soon as you Fire Up the engine... those residual Palm and Finger Prints will Permanently Burn and Etch themselves in the Pipes that are "Public" and will look quite unsightly on the Truck-SUV... Forever.
The Job may require more than One Day to complete... So "Temet Nosce" (Know Thyself) which means that Fatigue is your Enemy and to "Quit While You Are Ahead" once you get very tired from all of the labor involved. Start again the next day after you've had a chance to rest and recoup. You can see the Fatigue Mistakes that can be made in the Second Video when "The Tired Helper" completely assembles the under-cross Y-Pipe segments...WITHOUT having first slipped the clamps onto each Pipe FIRST... and this required a Complete Dis-Assembly-Re-Assembly and thus, having to start all over again.
Plan everything out well in advance and use Fully Enclosed Stainless Steel Double Bolt Band Clamps (...ubiquitous on Amazon and eBay for around $7-$15 a Pair)....NOT the "Horseshoe" U-Bolt Designed versions. The Former will Seal the Pipes from Exhaust Leaks MUCH Better... the Latter will crush and dent the pipes and invite leaks as a result of Over-Tightening the difficult Fasteners.