To be honest you won't find a budget exhaust, but make sure you change the X pipe.... If you only purchase a slip on system it would be a waste of money as you will have zero gains. Akrapovic is defo an option but very expensive.. Evolve valvtronic is another, again expensive. At the end of the day you have bought one of the most expensive chargers on the market.
I used to run the Akrapovic on my car but switched to the evolve not for difference of power but purely for sound. IMO the Evolve system sounds so much better and you also have the benefit of making it a little quieter with the press of a button.
Who is installing the GPower?
M3 E93 DCT, Space Grey,BC HB29 Forged Deep Concave Wheels, Ericsson Amuse F/R Bumper, Evolve Full Exhaust System, INTRAX Coilovers, STOPTECH BBK, Performance Steering Wheel,Custom Red/Black Leather Seats,///M3 ||Bimmerpost M3 Car Of The Month May - 2010
2010 R35 GTR