Wait a minute, you do realise the CSL let the M3 past? As per any other track day, if a faster car is coming, you part-throttle, or lift off to let them past on the straights? Besides, we don't know how modified this M3 is, or the quality of the drivers. About as unscientific as it gets.
Not particularly great driving, just standard track day fare. Didn't take any kerbs, car was never vaguely out of shape...proves nothing.
I had a drag with an M3 on, funnily enough, the M3 heading towards Portsmouth. I was annoyed that i only just outdragged him getting into 4th. Following week, i got the CSL on the rollers and found out the induction flap was sticking. I think it made something like 330bhp. Ultimately, the CSL weighs 100kg less. It is always going to be quicker. Supersprint cat-backs (and any cat-back for that matter) has been proven to give less power on the M3s. The only exhaust mods worth doing are the race cats and straight through centre pipes. Even so, we're talking a few BHP. This M3 would need a different mani, the CSL intake and better cams just to be on par.