well to get the most out of a stock quad is almost inpossable but there are ways frist eather a slip on muffer or a full exhaust i like dg i think there the best bang for the buck also white brothers if u u can find a full exhaust for 300$ grab it also rev box its a after market cdi that give u a extra 1000rpms and jet it u could also do a sproket change that should get u were u need to be also the rev box get a name brand like big gun there other chinas she for 35$ u have to change once a year thay just give out im running a rev box for about a year big guns and i can feel the power just off stock when i put it on i was 100% stock snaped the clutch like i use to and it almost throw me off u can feel it and that incesase like 5 to 10hp also know the diffrence i can tell of a 450 r and 400ex is tq even on stock and the ride the 400ex dose have adjustable shocks but the 450r for some reason even on the stiffest setting rides better than the 400ex when its on the lowest setting know the 250r is lil bit faster but we can fix that u can go on ebay and order a 440 kit comes with jug piston and rings gasket set the works know the stroker verson the ex wasnt never ment for it the head bolts are to weak u would have to buy a head bolts but a stock 440 big bore kit will work u can run stock can with stock lifters but if ur to it u u should do it right and just buy a stage 2 cam and valves and lifters jet it rev box and a sproket change u beable to do 65 to 80mph pushing it depending on sproket change

 

i meant 450r so u all know