RACE PIPE -Does size metters?

[racer]

I have 1G 2.0L NT Eclipse with headers downpipw and 2.5 inch cat back
and now i wana go with race pipe.
The thing is what size will be better for my car with the whole exhaust changed: 2 inch, 2.25 inch or 2.5 inch ??? Wich size will give me the best performance??? Tx for ur help guys.

 

[workin_on_it]

are you going to build up your engine more? do you want high end power or low end power? what kind of racing?
for the street, with no cat and straight thru muffler, i would recomend 2 1/4......still has good low end, and will help your high end.
if your going to use a cat and not a straight thru muffler, then 2.5 should be good.
2 inch is stock and there are 2 resinators and a cat with a non-straight-thru muffler.....quite restrictive.
before i did my exhaust, my pipe rusted out right after the cat.......low end suffered big time, but after about 3500-4000, it hauled!
now i have 2.5 from my header to a glasspack where the cat was and a straight thru muffler. no cat. it has good low end and helped out the top end alot, but not as much as no muffler.
it does sound a bit hond-ish after about 4000 rpm......but it hauls way better than before

 

[Mike1992]

2.5 to match the cat back check your pm 's ultra high flow

 

[racer]

workin on it i think u didnt understend me.I was asking about of road racing pipe the one that replace my catalitic convertor so instead of catalitic convertor i have strait pipe.I see u are talking about if Im going to use a cat?I have after market whole exhaust sistem and the only cat on it is the main big one that conects my downpipe with my cat back.

 

[workin_on_it]

sorry.....ive never heard of it as a race pipe.......usually as a test pipe.
getting rid of your cat will kill low end....especially if you already have a header and 2.5 inch all the way back...and i'm guessing a straight thru muffler.
but if you want awesome top end, then 2.5 inch would be the way to go.

 

[racer]

ok tx man but i duno my car still kick very hard on first gear after 2.5k rpm but it defenetly hit harder after 3.5 - 4k rpm.So with test pipe I'll gain HP but lose TQ?cuz now i have 115 Hp and 116TQ on the wheels so if i test pipe what it would be?