hi just got a xr 125 fitted a k&n cone fillter and have a preditor exhaust coming next week i have been told i might have to re-jet it what does that intail and where do i get the new jets can anyone help me P.s i get 65mph out of her only if i lay over the tank lol hope ithe new exhaust will help i would be happy if it would go 70mph so i gould keep up with the mad car drivers up here ! martin . Highlands Scotland