as topic stated, and i am not planning to change the catback anytime soon.

 

I don't believe there is a big point to it. The exhaust will just pressurize at the cat back mufflers. If you go 3", then you have to get freer flowing cat back exhaust.

 

but would there be any downside compare to 2.5" midpipe with stock catback?

 

Not really. Won't be a downside.

 

i do believe that the bigger piping you go with on a NA, you will get more HP gain on the high end but lose low end torque which our cars lack.

 

Only thing it will hurt is your ears, and those of people around you.

 

so if i run 3" midpipe with res with oem exhaust i would lose some low end torque? also with res it shouldn't be much louder than stock right?

 

Not seeing it. How would he lose low end torque ? Most midpipe/hi flow cat installs I have seen give hp pretty much across the board or at least fatten mid range, if little hp on the top end.

If you have a resonator it will still be loud, as the cat. acted as a second resonator, but less then a straight testpipe. I had a hi-flow cat w/resonator & it was a little louder. Now I have a hi-flow cat w/o resonator & it is really quite a bit louder. I have heard one with midpipe & Corksport exhaust & thought my ears were going to bleed.

 

so Fanman, in your opinion, u would say there is no performance diff from 2.5" and 3" with stock catback?

 

i will help some if i can... if you dont open it up all the way to the back, difference is going to be close to nill....

beers

 

Yep, little to no difference. 2.5" is plenty for a stock engine. Unless you open it up behind it no point.