Using the manley 221439 springs. I will say the cam has a fast lobe. I wanted to use the hollow stem valves from the beginning but was convinced to keep the solid stems in the heads, still might put them in. My big concern is the lifter pump up with .060 P/V on the intake side. The exhaust is good over .100. How tight have you guys run these things? It did have 15w40 in it and it did have 100+psi of oil pressure, another concern I was planning to switch to 10w30 or lighter. Has anyone used the crower or isky lifters yet? Are the johnsons worth $750? Just steep for a hyd lifter I think.