I put a new gasket on but when i looked at the stock one im sure it was re-usable, but better safe than sorry. My car also became significantly louder with the downpipe but i was hoping it would be a little more quiet. I am more of a quiet with a tone kind of person. How much do you think i could sell my greddy evo for. It only has about 5000 miles on it without scratches or anything.