i have a gd3 first gen and im looking at getting a cat-back on it. i'm leaning towards an invidia n1 and was wondering if anyone out there runs one on their first gen and what should i expect performance wise.

 

seeing that the l15 is basicaly the newer version of the old d15.
a few friends back in the day have had that exhaust, its pretty loud and obnoxious.
its a fart can. plz dont put that on your car.
if you want performance youl get at the most 2-4hp maybe more if you have flashpro. if you want exhaust and more hp. use flashpro and disable 2nd o2 sensor and straight pipe the cat. you can get almost $100 for the cat at scrap yards.
less weight, better sound, more hp, some $ in your pocket.

if you want a muffler setup. you can always take a muffler you buy into a shop and have them do any diameter exhaust you want. 2.25" to this...
Vibrant 1146 Universal Single Outlet Flat Black Muffler 2 5" Inlet | eBay