I need to put new exhaust on my 03 LS. I would like to swap out the engine at some point and put a 3800 in it. I am wondering if a new catalytic converter and downpipe for the 3800 will work on my 3400 for the time being. I would also like to put the 3800 "y" pipe and dual mufflers on the car. Can I just use the exhaust components for the 3800 on my 3400? I have seen that they have different part numbers at the auto parts stores, but I wasn't sure how compatible they are with one another as far as swapping.

 

The 3800 downpipe WILL NOT work with your 3400. But you CAN bolt up a dual from the cat-back and that will transfer over no problem.

 

Cool. Thanks for the help Chibi.

 

Why won't the downpipe work on a 3400? Assuming we're talking about ZZP's downpipe. The 3400 stock DP is 2.5 in and out from what I could gather. I did not actually unbolt it to check, just guesstimated with tape measure along the circumference of the pipe.

Am I missing something?

 

Without taking them out and comparing myself, I I think I can wager a guess. The shape of the downpipe (how it bends) from the rear exhaust mani to the cat is different. The matting position between the DP and the rear mani are not the same between a 3400 and 3800.

Again, with out a side-by-side comparison it's a guest based on what I've seen of my '04 Monte vs the wife's '05 Impala.

 

Guess it's a good thing I haven't ordered my DP yet! If anyone knows a thing or two about this, I'd love to hear it. (Or read it, more like )

 

the main reason is the 3800 is a 90* v6 and the 3400 is a 60* v6 the angle of the mount on the rear exhaust manifold is most likely different. also my guess is the 3400 DP will be longer vs the 3800 as the wider 90* would allow the rear manifold to go lower.

what mods do you have on the 3400 that require a larger DP? if you are seriously planing a swap... just go for it and save up. yes the cat back exhaust swap is a great idea.