Questions about 335is

I have a good friend who is looking into purchasing a 335is coupe. Now the thing that has me pondering is that he wants to do a 6466 FFTEC bottom mount turbo on the car.

My question is, can you backend flash these cars? These transmission slip after 460 wheel apparently so are there upgraded clutches for these cars and lastly can the transmission handle over 600+ if all the other questions are a yes.

Thanks