Evening folks. Ive got a 2012 1500 crew cab 4x4 with the 5.3 and 6L80. It’s my baby and doesn’t get driven much. I picked up a L92 6.2 for a steal because…well I had considered the swap for a few years now. Anyhoo, I’ve got hot rods and this truck is not one of them, nor will it ever be. Some of you might know me from LS1Tech, as I’m a mod over there and build some crazy crap. My question for those of you in the know is about exhaust manifolds. Is there a difference between the 5.3 manifolds on my completely unmodded truck, and a set of 6.2 manifolds that would have come on our trucks for this body style? I’m not going headers, so don’t ask. I know mine will bolt up…I’m referring to a performance gain from the 6.2 manifolds, compared to mine. I can’t find GM part numbers to compare the manifolds to. Same manifolds? Different manifolds? Give me your knowledge my truck friends!

 

6.2 manifolds are the same part numbers.

Half the time just use Rockauto to reference part numbers, makes it super easy.

 

Awesome, thanks. I was hoping that I could use the same exhaust to keep the install super factory looking. I’ll just use the manifolds that are on the current LC9 5.3 in the truck, when the time comes to do the swap.

 

as a second opinion: without knowing GenIV setups that great, they definitely used the same GenIII manifolds from 4.8 - 6.0 engines, so i can't imagine why they'd change their business model. even if the 6.2s had higher-flowing manifolds, it sounds like you ain't working the truck hard enough to notice a difference.

for instance: my car's got a TVS2300 on its little LS1, and i'm using 1-7/8" primary headers. it breathes great all the way to redline putting down nearly 700h / 670tq. i also know a guy with the same blower on his LS7 using 1-3/4" headers. it still made nearly 650 wheel torque... except it fell on its face above 5000rpm.

 

I'm gonna DOUBT it's the 1-3/4 PRIMARIES corking that motor...
IF the exhaust is stifling it, it's what comes AFTER the collectors... ie Mufflers or Y pipes need to be BIGGER.
700 WHEEL is going to WANT DUAL 3" pipes or 4" single pipe

 

it's been 10yrs since i studied his build thread, but i thought he had dual 3" behind them... if not, it was at-worst the stock dual 2.5".