Turbos are a two edged sword...
* More fuel efficient
* Easy to get BIG power
* More heat
* Too hard to not modify due to low cost/power ratio of modifications. Once modified you either have to lie to keep your warrenty (not my bag) or have potentially high $$ warrenty claims fairly denied.
If BMW can keep the heat under control (a hard 1 hour on the track without temp problems) and maybe a Dinan tune with matched warrenty, the new M3 could be a winner, especially if it wieghs less than the current, like the F30 vs. E90 328/335.