As much as I don't like the look, I'll probably end up keeping it... I'd guess the M3 front clip generates additional downforce, so I'm guessing the rear lip spoiler is there to keep things equal.
2006 Corvette Z06
Black / Ebony - 459RWHP / 438RWTQ
2005 Subaru Legacy 2.5 GT Wagon
Brilliant Silver / Tweed M5 - 229AWHP / 260AWTQ