i can't remeber the exact things we did to that bike ,but it had a supertrapp exhaust,some sort of baja cams that were being produced at the time (may have been crower,sounds familiar?) upped a point compression @ .030 over. airbox mods,and bigger carbs. i forget the exact gearing but 15/45 sounds familiar? well anyway we had some cam 2 race gas left over from the race car and filled'er up and hit the highway to see how much difference the fuel would make, well thats what it really needed! woke that puppy up.... i passed that cop and didn't see him (as my face was buried in the speedo) and when he finally did catch me (10 miles later),he actually let me go(after a verbal scolding) as he was a fellow dirtbiker and could not believe that a dirtbike could go so fast .....but i definately ran out of HP as the bike was still in enough control to go faster Sensational! I got a good mate that I always bag out with a XR650R. I went quiet the day he let me ride it, 70 rwhp does alot for the senses! I am pretty sure 15/45 is standard gearing on the BRP. My mates want to run AVGAS in their YZ450's because we can get it nearly half the price of 95 octane premium fuel. I have read it don't do much on a 4 stroke but on my YZ125 I could drag it with the other 250 2 smoke's. I can get about 170kph (105mph) out of the WR with 15/50. I too think HP is the limiting factor as it is not really reving it's tits off at all. Plus it has to haul my fat ass down the highway but it helps with the wheel spin!