UNSANE, I have streched them to 110 hrs. I was a little worried about the valvetrain since that is the weak link. I rebuilt the ones in the Nashville Cats before the season with only 68 hrs. I knew they had been and will continue to be run hard because the boat is so big and heavy. We have quite a few poker runs to make this year and I did not want to rebuild during the year. We put over 9 hrs on them at Jax alone. We ran almost the entire first leg at 6200 rpm. I think that was somewhere around 30 miles.