Having difficulties with my 2010 BWM 335xi

[mi2232]

So, i recently got the car, i have changed the spark plugs and ignition coils on it and the car is straight-piped. The problem with the car is that if I step on it and floor the car for even 10 seconds lets say, if i go and park the car and turn it off, later i can't start the car. Usually I would have to wait for about 1hr30 - 2hrs before i can start the car again. I don't understand what the problem seems to be. It would be great if someone can explain where the problem might be and maybe give me a solution for it. Thank you.

[MauiM3Mania]

Mowed post to the model specific sub-forum.