Hi guys, Today one friend give me a stock subaru 05 sti Japan exhaust muffler, do you know if will fit on the 5? I realize that the sti exhaust diameter is bigger I think its probably 2.5 inches, so I'm planning to change all exhaust piping to fit it, removing the second cat at the same time. Any comments? Do you think it will have a low increase in HP or torque? thanks in advance.