Ok so right now I have the 3.75in catback by Apexi and it's extremely loud and it catches everyone's attention including the cops. If I were to change the Catback to a 3in would I need to retune my car? Would I still be able to run 15psi and get 418rwhp? I've got a 3in from the turbo all the way to the midpipe then it turns 3.75inches.

Also, I don't have the thing that holds the presilencer in the catback. Does anyone know where I can get that? Thanks a lot!!!

 

just buy a resonator then put it in the mid pipe, also if that is to loud go with the RB dual tip, its quite. I had/have the same problem i quite mine down with a resonator and change the apexi to a HKS dragger.

 

Would I still be able to get as much power though or do you think I would need to go for a retune in order to find out my new power levels?

 

If you narrow the exhaust you will lose a bit of HP. It will vary on the application. I lost 18 RWHP from a pettit racing turbo tuff (3") catback to a RB dual (3") catback. Restiction will hinder performance on the same tune. As far as needing a retune the restriction will make you run a bit more rich so you wont hurt anything. I switched back to the single tip. I hate the look but would rather have the performance. G

 

I would love the performance, but it's just too dam loud, however, I guess I can just run a presilencer.

 

in theory

smaller exhaust = less flow = less air = less power = less fuel needed.

in reality, you are at least going in a safe direction, car should at least be checked to make sure its safe, and retuned if needed.

 

i may be mistaken, but since the rest of his exhaust is "bottle-necked" at 3 inches, does it really matter the size of his catback?

 

Yea, that's exactly what I was thinking ^

Also, does anyone know what the things I need to hold the presilencer in the catback are?