I have a street legal '07 CRF450X. I have several friends with dual sport bikes such as DR650's, XR650's, etc, and they are always planning rides that require a significant amount of highway miles (20 to 40 miles) mixed in with the back country legs. Of course they are always inviting me along on these rides, but I feel leary about riding my 450 on the highway for that long. Obviously, the seat is not all that comfortable to just cruising along at highway speeds, and I run nonDOT knobbies. But I am mostly concerned that riding at highway speeds at constant RPM, etc will take a toll on my engine. What do you guys think?