Yes I know they must be getting old. All I would like to know is if a 3in catted downpipe would flow alot better than a 2.5 aftermarket one? It is only .5 inches does it really matter?

 

Not that I'm an expert, but the running theory right now is that with these small motors/turbos and power levels where they are at, anything over 2.5 won't help much, if at all.

Seems like most people pick based off of cost and sound, rather than size.

Edit: didn't see the word downpipe the first time through. That I am not sure of.

 

A 3" DP will flow better then a 2.5" one. For a stock Turbo, most people received better results (HP/TQ) from a 2.5" DP. The Turbo Mini Motor likes a little back pressure.

 

Same old can of worms just got opened.

You'll find two answers, both in disagreement with each other.