Yamaha says my TZR will do 45mph derestricted. This is complete rubbish the best ive got out of it is 23mph, yamaha says it might be due to my weight, i found that quite offensive and obviously incorrect as i am only 37 stone. i put an arrow exhaust on and re-jetted also k+n filter the only problem now is the mirrors vibrate at mach 2 and on a recent run the bike lifted off, well i can tell you that yamaha´s claim of 45mph was the last thing in my mind as i passed the space shuttle discovery, imagine the suprise on the astronauts faces to see a TZR 50 looming at them after over taking a meteorite and all i could think about was how am i gonna get this baby back to earth.