camshaft lobe surfaces have high loadings and relatively poor lubrication, so initial running in is critical but if the parts were manufactured correctly they bed in quickly. I would suggest at least 100 miles below 6000 rpm and then another 150 miles progressively increasing rpm. I have just had the engine rebuilt and some headwork on my 998 and i am following this regime. I will still be taking it on track on easter friday even if I have not reached 250 miles but will use higher gears and lower revs. although you dont get massive drive out of the corners it makes you focus on corner entry speed and corner speed which for the first trackday of the year is no bad thing. I would check with whoever is rebuilding the engine in case they have a different opinion. dave |