If you want roar then you need an open cone filter, such as a KN typhoon etc etc.
This will however probably loose you power due to its capacity to suck in warm engine bay air!
If you have an R53 S (older type) then you wont get roar..the inlet and supercharger drown out anything with whistle and whine.
If you have R56 then you stand a better chance of roar as the turbo doesn't get effected as much by the intake...againopen cones give you roar but often loose power in the bay of an S due to heat from forced induction units. Shielded intakes with open cones in are the way to go but you loose some of the suck and roar noise.
I have an R53 MCS and run an Alta CAI in mine...its deafening as it goes by cos the charger and throttle body cause huge whine and whistle due to the intake
