I already have a set of ductile iron rocker arms and didn't want to fork over another $$$ for the ones required for the TF heads. Also, I don't want to run roller tip rocker arms. I am doing all I can to minimize the number of moving parts as well as reduce reciprocating mass. From all I've seen, the TF heads flow better, pretty close though. I'm quite happy with losing 50 lbs and gaining about one point of compression with aluminum.