So the most common upgrade from our dinky stock downpipe is to change it to full 3 inch downpipe. What would happen, or should i say is it possible to have a 4 inch downpipe? Does downpipe size work with how big the turbo is? I ask because i was watching a movie and a sti listed it mods and his downpipe was 4 inch's.

Jordan

 

Theres almost no reason to do it...

you acutally might lose power.

3" Turboback is the best way to go.

 

Unless you're running a GT42 turbo, there's no reason to go w/ a 4" downpipe.

I'm running a GT30 now, and will probably switch to a GT35 eventually, and a 3" is still more than enough.

3" for the stock turbo is PLENTY big.