Itb's needs cams. In a n/a situation these cams have lots of over lap and duration. However, i recall from somewhere that turbos do not respond well to lots of overlap. So...whats the solution for a turbo with itb's.
turbo cars don't like overlap because that is when your intake and exhaust valves are open at the same time. given that the intake side of things is pressurized, if both sets of valves are open, your air/fuel charge will blow through and out of the combustion chamber and never get lit by spark.
that said- the m42 has adjustable cam sprockets. if you find yourslf limited by the stock cams and need something more aggressive, and the grind profile has overlap when both cams are at 0deg, then advance the intake cam and retard the exhaust cam until overlap is gone.
i have itb's now, have most of the turbo bits ready, just saving up to get it all put in. i think i'm going to be fine with the stock cams... but your goals may be different. if you are trying to make peak power above 7000rpm, then i would worry about the cam profile. otherwise i think you will be OK with stockers.
