Check out the forum section on forced induction.
It depends on many factors.
But you still need the high flow mass air meter and cold air intake and high flow injectors to go with what you have.
The entire pacakge (non-forced induction) is about 60 -70 HP gain, IIRC. So about 300 - 310 at the crank.
What are ouy trying to do with this thing? BMW are about balacne, handling, brakes and power all in balance.
'95 Alpine M3 LTW
'00 Dakar M Roadster
'02 Topaz M3
Red/White SRF #4 (Chassis 561)