Hi im looking for a performance exhaust system for my h3t 3.7l. Ive been researching and calling companies for days now and i just cant seem to find any! And when i do its always for the alpha. Im putting a cai in and looking at couple different headers and would love to compete it off with a good performance exhaust system. Either do this or drop in a 5.3 and new tranny. Would like to not start the swap till spring of next year though.

 

i found these 2 but they seem to be just a direct oem replacement not performance exhaust.

 

You are not going to generate any significant performance improvement with an exhaust system change itself, especially with an I5. It is more for sound/tone than anything else.

However, if you pair a better flowing exhaust with an Intake, PCM Tune, Efan conversion, Port/Polish Throttle Body, it will compliment those nicely.

You might have to go old school, visit a local performance oriented exhaust shop and see what they can offer. Not a muffler repair shop, but a shop that does customs and race applications.

I would not bother if you truly intend to do a V8 swap. I would not bother with a motor swap either. Sell the I5 and find an Alpha H3T, do the performance mods to that. Lot less headaches and known costs to get to complete reliability. Even if you do all the wrenching, a motor swap is going to turn into a money pit to get it right even if it all goes smooth (which is a maybe).

 

Thanks Doc for the info. Already ordered your intake and am in the process of getting the tb port n polish. Want to get the better high flow exhaust befor i do the pcm tune. Just having an extremely hard time finding one. I did find a billy boat that fits the h3t just cant find any reviews on it. As far as the v8 swap i kinda gave up on that as ive spent all summer sinking like 20k into my 2018 silverado engine bay. Just want the hummer for when my truck is down but also would like it to run the best it can.

 

I do not personally know the particulars of the Billy Boat H3T exhaust, but overall BB does quality work and their systems for other vehicles are well received.

Sounds like you are well on your way.