I may of been harder than I needed to be on the heads.Basically you get what you pay for.I have pulled 3 rockerstuds out of mine running a cam that is well in spec for the spring set.I couldnt imagine how much trouble you would have with these if you actually ran a roller cam with the roller springs..(Higher spring pressure).It takes some work to get the ports to match any intake and the geometry is not as good as it could be.They are what they are.A cheap knock off.People use them and there are those that have alot of luck with them.This is a perfect example of getting what you pay for.When I put this engine together I saw them and the price was so tempting I went for it.I only wish dart,brodix and afr would be alittle more competetive with their prices.Their quality could eliminate some of the knockoffs, its the price that keeps these things alive.Nobody in their right mind would pick the procomp over the dart if the price was anywhere close..Take care