5.9 build

I just looked on the PIE website and there is no flow data on the Stage 1 heads but the Stage 2 description has a flow chart that hits 290 CFM from .500"-.600" lift and 212 CFM at .300", which is pretty good. Flow isn't too far behind a TF head. I'd say that if the chart isn't lying, the Stage 2 heads could easily support 500+HP if the rest of the parts are capable.