Here's my M3 GTS. I tried to replicate the real one as best I could. The weight is 1489kg which is one of the many weights I found for the GTS (1490-1530). I used only weight reduction 1. It has 450hp (like the real car) after the first oil change and engine tuning stage 1 and Titanium semi racing exhaust. The sport soft tires are on BBS RE-MG wheels painted "Black" (from Ford Mustang or Chevy Camaro). It has the front splitter lip and the smaller of the two rear wings. I lowered it the 16mm front and 12mm rear that the real car is lowered from stock. The top speed is 190 on the real car, and the full custom transmission's stock setting is 193 mph, so i left it alone. The orange was hard to find. But I think the perfect orange is "Glutorange" off the $68k Audi TTS. Its even German paint.
References: http://www.m3post.com/forums/showthread.php?t=318714
Here is my Frozen Gray M3. All stock except for sport soft tires, the BBS LM-R wheels, and Matte Silver paint. (I wish there were more BBS wheel options, Im not a huge fan of either wheel when not painted black)