So then sir, you'd like to buy the performance exhaust from BMW eh?
If that's the case, perhaps you'd be interested in a product I recently came across in my shed. It's called 'NoisoRub' and appears to be made from distiller snake oil. In addition to its ability to prolong the life of all engine components (when applied liberally by a teenage virgin) it also has the welcoming effect of making all BMW engines sound like the M car above them.
So, of you drive an M3 and have a teenage virgin rub this into your back box, the car will instantly sound like an M5. If you do the same with an M5 or an M6 then I've heard they will sound like the BMW powered F1 cars from last season - but I can't confirm that as I've not got an M5 to try it on.
One of the great (and totally unexpected) side effects is that when the teenage virgin hears your 'new' M car sound, there is a 1/3 chance she will ask you to penetrate her after only a couple of dates. Great news!
I've used almost all of this stuff myself, but I have just a few litres left and as your a special forum discount awesome friend I could probably let you have 100ml for only £24.95 + £175.05 postage and VAT at 20%. I'll do you a discount if you want more too, because postage can be combined.
I can't help with the teenage virgin though! I used all mine up when I turned my 1.4 Nova into a VXR8 powered beast by applying multiple coatings of 'NoisoRub.'
I hope that helps mate!