i know plenty of people running the m2's without upgrading the valvetrain and report of no problems. i guess if you don't run at the rev limiter all the time, it should be fine. if i were road racing the car or shifting 8k+ rpm then i would definitely upgrade the valvetrain for added reliability.

 

wow, this thread got pretty side-tracked since the first page.

i say, go with cams first, then turbo.