Are you after a ZZZZZZZZZZvrROOOOM or a BRROOOOOOOOM or more of a throaty VRUM VRUM?
(I'm losing the plot a bit here so in English)
What sort of noise are you after or do you just want the power gains from a sports exhaust. Have you thought of a SPORTS CAT as well? Are you looking at getting a full exhaust system or just the back box?