I believe the heads were done at a ford shop near John Pennington's home. This combo was freshened by Ryan Johnson at Shadydell speed shop and he posted the combo on here. Ryan was surprised how simple this motor was and how much HP it produced on his Dyno which was a very conservative 670 HP. I think what this shows you that if you pay attention to details,(Heads,Cam) and get the rings to seal well you can make big HP. I believe that Ryan has been doing the 2.15" intake on some of the Indy engines he has been building and likes this head mod.-Randy