Yes I already did the SX head and a FMF pipe and sx cdi it sure woke it up! I think it wont be a 500 but it will be at least an equal for a 450, I belive dirt rider tested one at over 53 hp which is about what most 4 strokes make, just a different kind of power! I tried once to ride a yamaha nitro135 hp and my polaris pro at 143 hp !! I think I will keep the polaris! A two stroke is designed and built to run at 7-8K rpm all day long, they are tuned for that RPM the oiling system is calibrated for those RPM, it comes on the pipe at those RPM's I dont think it will do it any more harm running at the upper RPM's than it will in the dirt, I used to race my 250 on the pipe every weekend and rebuild once a season,, nature of the beast!I dont understand why everyone is so afraid to run a 2 stroke on the pipe? Four stroke has a red line to keep the valves from hitting a piston a two stroke is limited by the pipe its tuned around! The KTM also has an adjustable power valve so you can change the way it comes on the pipe,make it peaky like a MX engine or tractor like a 4 stroke!! I bet I could change rings and a piston in an hour in the trailer! Not on my BERG! I think I will just turn up the volume on my I pod and just feel the power the the 300 hunny has and just keep smilling! When I first spoke with Alen about the TS A few years ago some of the guys were running a 300! We were talking abput HP in relation to a sled,, and I realized then that bikes were not about HP but about riding finess, so when I go up in the trees I will zig zag one more time than the big bore 4 stk,,, mabe!!