I agree, the M3's I6 is one the most powerful six cylinders around. The point I was making is that the "masses" will never see a NA I6 in the upper 200 HP range from BMW. BMW has no intentions on boring the 3.0 I6, so they've almost hit the ceiling. The current M3 engine is special, but it's not cost effective for BMW to continue with it, thus the change to a v8. FI might be the answer for BMW. I'm not sure, but I think this is not an area of expertise for them. Anyone else knows about BMW and their history with turbos or superchargers?

 

Well the 3.0 liter I6 was bored and made to a 3.2 liter I6 which is used in the current E46 M3! Now FI is what BMW does not like at all, look at all of their cars taking NA motors to compete with heavy hitter cars FI and NA such as the high revving V10 M5 to compete against the E55 AMG. There have been previous turbo diesel BMW's back in the day and maybe a few still in europe, but none in the US or out in the past 5 or more years! Also the McLaren F1 racecar or even road car uses one of BMW's or BMW's most powerfull ///M powerplant engines