I have heard a Stillen CBE in person here....It sounds nice and is hella quite at crusing speeds...Only growls when you get on it....Other than that if you're just crusing you wouldn't be able to tell that the Z was running an aftermarket exhaust..Like m4a1mustang, I really don't like the tips of the stillen, but if Red370 is right and you can readjust them, then it might make up for the fugly look!

Just installed Stillen CBE only on 7A and it is exactly what I wanted, There is
just enough more tone when you drive normally to know it's there. Dead
quiet unless you are on it. My wife has very sensitive ears to any drone
and she has no problems with this exhaust. By the way it is not ugly like
someone else stated. If you like the NISMO exhaust looks you like the Stillen. I may-----try the HFC which I know will make it more aggressive
but right now I am very happy with what I have.

haha to be honest one of the reasons I want an exhaust is because I'm tired of listening to the tires on the highway...seems like the Fast Intentions is the best best as far as price/looks/gains/sound....