Why is it that my R125 wont get past 65 MPH? I'm guessing it must have been since I've fitted my GPR exhaust system I reckon. Since I fitted it I've barely gotten time to go out for pleasure ride or thrash as I call it. Its all 30 MPH round town riding. So I've not known until yesterday when I went for a "thrash". The acceleration is awesome, but top end has gone pants. Is this due to needing the fuel air ration sorting? Would a K&N filter give me back my top end? Any suggestions would be great as now I may as well be riding a Peugeot SpeedFight for top end fun.