i have the greddy SP on my car, it is super quiet. but when you get around 3k rpm it has a real deep tone. like subwoofer bass tone, nothing like honda fart can. you WILL be able to hear your intake ( if you have it) and your engine over it, but i think its great. i have only had one problem with the system on my 91 240 coupe... the muffler itself is so friken huge... the bars that come up to hook onto the back two rubber pieces is right up against the fuel tank brackets or somehting metal there, and since it makes a bass-sounding tone, it rattles REALLY bad on there, but i got a piece of rubber and stuck it in there and it sounds fine now
any more questions?