Originally Posted by gr8stevo

Here is a clear answer. NO you don't need over size valves or porting. I am currently running stock size intake valves, stock exhaust valves and a stock head that is not ported. I have ran as fast as 177mph with this setup. I would guess its making 1000+hp . Also have seen 11k+ rpm and my average gear change is at 10,800rpm.

I will say it took about 5psi more to achieve those numbers compered to a fully ported head with oversize valves. Remember boost is a measurement of restriction.

Long story short there are gains with good port work and over size valves but you can spin 10k+ and make 1000+hp without it.