I am a bit confused as well as to why BMW did not just throw a turbo on a v8 and call it a day. The motors would probably be around the same weight it seems
Ultimately what I am hoping is that BMW did not max this motor out, I would love to be able to throw on some catless down pipes and a chip (or actual dyno tune) and have the car put down an extra 50hp/50tq to the wheels. It would be a huge disappointment to gain only minimal power because the motor is already significantly maxed out stock by BMW.