I can only speak from my experience. I purchased a set of their H-Beam rods for a budget 451 that I used to run. Had them checked by my machinist and all the weights were spot-on as well as the lengths. Had to lightly hone for the pins. I spun that motor to 7,400 rpm. I had a lot of valvetrain problems along the way, but that's another story. That motor went 10.20's in my Dart Sport. From what I read from others experiences, I might have gotten lucky.
