BMS is cool, sounds amazing and really enhances the standard 'noise'.
I am waiting for the Riss Racing intake as I have heard good things.
Not sure about the BMS dual cone, as there really isn't that much difference between the single and dual.
Listen to this cheezy noob on YouTube
The review is iffy, but you will hear th sound.
Born 30/04/10: MY10 135i M Convertible, AW, Coral Red, Logic 7, Elec Mirrors, Ipod USB, Xenon's, Heated Seats, Wind Deflector, BMS DCI, JB+, BMW Performance: Exhaust, SSK, Handbrake, Pedals and Shadowline grills
Gone! MY08 135i M Coupe, AW, Coral Red, Logic 7, Xenon's, Darkened Glass, Ipod USB