[morepowerjoe]

I have hollow intake valves in my l99 stock port heads. I got them because I read that they will give you like 3-400 rpm higher rev range and I wanted to rev mine as high as needed for my peak power set up. My tuner said that only use severe duty oem valves strictly for durability (but they let me bend the rules a little). My power did carry out to 6700 rpm before starting to decline. So I don't know if they were worth it or not but with your set up I would spring for a set because they aren't really that more expensive and I think it will help you get over the 6k rpm mark if you want to.