The fact that we have one guy running them sucessfully does not, in itself, provide enough evidence that they are the choice for engines built up to the 600 HP range. This is no reflection on Ron, but I have read enough stuff to make me a bit wary. I would love to hear some specific experience from folks both Pro & Con on their experience with them. I am also including any of the other available I beam 5140 rods out there. I have made my decision, but I am sure there are others out there that would like some more feedback.