And remember, it is not just the cams. You need to do the entire intake and exhaust for the cams to be able to do their thing.
We did the Turner Stage 4 kit on our M Roadster (2000 S52). This is the Shrick cams, high flow injectors, high flow mass air meter, cold air intake, and headers. The car already had a Super Sprint on it. Supposedly good for about 70 HP. Enough to make the stock clutch with delay valve a little dicey.
We opted to NOT do the M50 intake manifold, as it makes more power up top, but less under 4000 RPM, so for street use, we opted to stick with the stock S52 manifold.
If you autocross, check your rules first. You may be moving yourself into a MUCH higher prep level with cams.
'95 Alpine M3 LTW
'00 Dakar M Roadster
'02 Topaz M3
Red/White SRF #4 (Chassis 561)