step 1: buy vanguard exhaust
step 2: buy quads, cyba has good ones
step 3: find local shop to install, your diffusor would need to be trimmed or you could buy an aftermarket quad style
step 4: ???
step 5: profit
2007 Space Gray E92 335i 6 speed
Last edited by deluxe 247; 03-03-2013 at 07:08 PM.