Fahad if you're looking for more power and sound youd be better off with some track pipes, much cheaper than x pipe and give more power(and sound).
500$
http://www.europeanautosource.com/pr...k-pipes-e9x-m3
IMO: I would just swap the existing axle back for a slightly louder one to suit your taste. Just beware, the gt2 is insanely loud, Ive ridden in an m3 with the gt2(titanium) exhaust..to much drone, get the regular gt.