That was a good video, and as I am a BMW tech I have driven both cars. I installed some Dinan software on one 335i, felt like it lost some down low power but pulled very nicely up top. M3 really does need some more TQ, I know I get used to my 03 cobra but the M3 really is very weak down low. With that being said the M3 does weigh more than the cobra but it does not feel it. M3 would tear up a track for sure, fun cars but $70k+??
Just like the video states, the 335i will almost match its performance for much less.
I have a Dinan 335xi coupe only the ECU reflash though not the suspension that car had. With that being said if I had the extra 15-20k the M3 costs I would have bought that and not thought twice about it. The overall package of the M car is much better.