I now what a R75 has for power, The same as a r72 330 hp. It was not my dealer that dynoed them it was cummins. They did my two machines and about six other peices of equipment. One was a STX 450, it was hitting 480, jd6950 choper book says 550 hp it was hitting 625 and two peterbuilt's 470, they were around 530hp. The cummins guy told me that there engines were going out on the high side, and they were going to corect those machines. I had to sign a waver saying that i took full responsibility to the engiens if any thing happened to them, if I wanted them left were they were. As of this date they are sill 385 hp and have 1500 hours on them not bad for 2001's. I have had no trouble with them at all. When i trade this year I will get cummins to turn them down. Colin