Make sure not overfull of oil

Yep, check your oil levels. Are your breathers clogged up?

+2

Breathers could be clogged

Like most have already said, it could be a couple different causes, or a combination.
Check leadowns.
Overfull of oil can create excessive windage, which can create crankcase pressure and pop out a dipstick.
Your breathers could be clogged, but this woudl more be a symptom of excessive blowby or windage clogging them with oil. Check them anyway.

My engine, 598ci N/A, would pop the dipstick out at 6000rpm, but would not blow a drop of oil out of any of the valve cover breathers. leakdowns at 4% or so. Put a locking dipstick on it and problem solved.

Lokar makes a very nice billet locking dipstick, reasonably priced as well.

if you do not have a lot of leakdown, you need to get the engine to breathe better..had the same issue on mine with procharger, changed to 5/8 hoses off both valve cover to blower intake cured mine totally...

What do you have for breathers on the valve covers? There may not be enough crankcase ventilation.
Eddie

I thought breather in valve cover were there to exhaust pressure from crankcase, not to breath from those valv cover hoses... was I wrong?

They both do the same thing, relieve pressure from the crankcase. Sometimes those hoses to the flame arrester just aren't enough. Especially if you increase your cu.in.'s.

on prochargers, they run right off the fittings on the valve covers to the the air bell on the supercharger, when mine were 3/8 blew oil out of dipstick...changed the fitting and hosed to 5/8 cured instantly...that pressure has to go somewhere..better blowing the dipstick than the intake end gaskets..which will as well....