Custom catback: 2.25" or 2.5"?

[supermanx58]

So my coupe is a 2.5s and I'm planning to get a custom catback exhaust real soon. From reading other posts, it seems that the stock piping diameter is either 2" or 2.25"? Some recommend getting 2.5" but even more said 2.25" would be better. For increased flow and hp gain, wouldn't 2.5" be an actual upgrade and thus better? Only other mod right now is a K&N intake.

Also, does having 2.25" or 2.5" matter in terms of having that ugly raspy sound? I want a deep throaty sound that's not overly loud.

[YoungCoupe]

You're correct, 2.5" would be the better diameter in terms of performance. Bigger diameter = better air flow. That being said, there is a very negligible difference between 2.25" and 2.5", especially on our 2.5s.

I believe a 2.5" would have a deeper sound, but don't take my word on it.

[supermanx58]

Ok cool. Leaning towards getting 2.5" now. I wonder why some people prefer 2.25"...

[aphu]

i have custom and went 2.5 piping throughout. sounds amazing

[mikethemike]

I have the nismo catback and I'm happy with it. Its also 2.25'' piping. With that said, I can't say it sounds better because Mr. Aphu up here would beg to differ. Its all really you personal taste man. Check out some youtube clips, throw on some headphones or whatever just so you can get the best effect because unless you live in an area where there are AC meets, youtube videos are you're best bet for results.

2.5'' - Louder, more airflow but a liiitttttllle raspy for my taste, but not fart can raspy, not at all. All in all, some do sound really nice. Just not for me.
2.25'' - Deep, not too loud but definitely noticeable tone. Little to no gains.