Ok guys 'n gals, I got a few weeeeeird questions for you.

Assume the following for all questions; Its an 05 evo stock. The type of answers I'm looking for is how will it affect spool up, TQ, and HP.

1) How would my car react to having a 1 1/2 inch exhaust?
2) How would my car react to having a 4 inch exhaust?

As I under stand things, the larger my exhaust, the less backpressure, the slower the spoolup, the more TQ loss but more HP gain. Does this sound about right?

 

NO, come back when you have a turbo car...

 

when you say exhaust, you're talking about the pipe diameter or the exhaust itself?

1.5 inch exhaust... Get one and let us know.

Turbo cars don't need backpressure as much as some other cars, since turbo system recycles the exhaust gas.

Anyway, don't put 1.5 inch exhaust. there are 1000000 better ways to get power.

 

1.
2. most of the time you gain torque as well hp when changing to a larger diameter

 

well, that's not true on banana's #2. You need to take in more air to have any sorta use for bigger exhaust.

Freer flowing is good but that could be accomplished by cat delete. But if your intake mounts to say 5 inch diameter intake tubing, that means you better get 5 inch diameter exhaust.

If you're using stock intake, 2.5inch tubing, then you could make enough power on 2.5 piping without sacrificing low end torque.

This is of course on level one tuning.

 

search

 

i sit corrected

 

i should rephrase my #2... Too large is not good either. I think it only makes sense to get a 4inch exhaust is to have a massive turbo set up. For example on a car equipped with t88/to4r. I just viewed 3 different evos on the importtuner power pages. Each one gained atleast 15 torque with a downpipe without upgrading the air flow except a IC in one.

 

Well just to set the record straight, i'm not going to put a 1.5 inch exhaust or a 4 inch exhaust on any evo.

I am just trying to get generalities on the disadvantages on each.

I should have clarified that I was thinking of a stock intake, stock turbo, and full 3 inch turbo back exhaust with either a 1.5" muffler/tip or 4" muffler/tip. I know this is an absurd idea which is why i'm not going to do it, I just wanted to know some basic characteristics of what each setup would yeild on a dyno and actual road results.