Ran at VIR with a Boss on slicks. He had adjusted the suspension at a professional shop, I'm assuming the Boss comes with adjustable coil overs stock.
So he had a little more power, a bit more grip and probably lower CG on stiffer suspension. Aside from the difference in lines (his was better no doubt) I could tell my car would lose ground with every corner. I just could not keep up, stock M3 with stock suspension on 265/285 tires. And I was outbraking him...
Maybe if you do a suspension on the M3, plus bolt-on mods and slicks you will run similar times. But don't kid yourselves guys, 9/10 you pass the driver not the car. I passed a gaggle of faster cars, Vettes and Porsches and whatnot, but in each case I was simply driving better than them, or having more confidence which is huge for an amateur on a track.
And I have to say, it didn't bother me in the slightest. I had an incredible time, didn't break anything and went home in the same gorgeous car I'd come in.
(All else being equal, he would have still been faster than me, he had no fear and was jumping the big curbs in the climbing esses, which is asking for trouble IMO and I would simply not do in my DD.)
2009 E90 M3 ED
2014 X1 28i ED