stock 05 400ex vs the other 05 ex

[plsports]

hey guys im a lil boggled here.... my buddy just bought a 05 400ex after i did and hes been ridin just as long as me if not longer... he has always had a4ooex i have not. well we were up in wisconsin this weekend up by blackriver falls and well he has a full hmf system he just bought with a dyno jet kit wit the needles n everything along with new airfilter and no lid on his box... i put my quad back to complete stock before we went up to wisconsin well when we were on the straight trails at a stop we would go from a stop and i would be neck and neck with him... his quad runs great ive rode it so i know its not jetted wrong. after seeing this i was like screw buyin all the mods ill leave it stock for now cuz if it makes that lil of a difference im not spending 500+ like he did... whats the deal with this?

[400exredrider]

top speed probably wasnt effected much but im guessin it has atleast more torque not to mention a better sounding quad

By adding a pipe and jet kit to bike your not really going to go a whole lot faster, however you will get rid of that annoying jerk when you let of the throttle. Everything will feel smoother and you will probably notice more power in your lower gears. Piping your bike is worth the money i think you have to let the motor breathe. You can't expect to walk all over a stock bike with a pipe and a jet kit I think the most I've ever seen is like a 1 horsepower gain at your peak. I think the 400 stock hits about 26.9 Horsepower and with most pipe,airfilter,and jet kit combos you might be able to touch 28 Horsepower.