I ran a set of Dave's heads [ Stage I ] on my old Duster. I supplied the cores [ I think they were 974 castings ]. They were delivered on time and worked well. I picked up 5 mph in trap speed and dropped the ET by .5 sec. The previous heads were poor, but .5 a sec and 5 mph is still a pretty good improvement. I later sold them to a friend [ Dare Dude ] and he used them on his light weight Dart drag only car and went mid tens with them. Not too shabby.