3500 is about the limit on stock valve springs, depending on the throttle position and boost the smarty will let the truck run all the way up to 3400 (same on the 5.9's) much over that valve float may become an issue.
I don't think they are has heavy of a rate as on a typical gasser motor. I haven't seen it personally I am just reiterating what i have heard others say, it could be wrong. I do know with high boost levels and high RPMs valve float becomes an issue.
A forum community dedicated to Dodge Cummins Diesel truck owners and enthusiasts. Come join the discussion about reviews, drivetrain swaps, turbos, modifications, classifieds, builds, troubleshooting, maintenance, and more!