Despite what ever gains you get, very few mods are worth the money in terms of HP gain. Best thing I did on my X was drop a tooth on the front sprocket....made it peppy as hell (I realize this has nothing to do with HP). I got a buddy who is dumping money into a z400 tryin to make is faster than a raptor 700...should have just bought a faster bike...but every time he puts something new on (most recent was a pipe) he asks,"so do you think ill be faster than tyler now?" Hell, Im still faster on my 21 year old R....tuning...make the engine as efficient as possible, no as expensive as possible.
"Always do sober what you said you'd do drunk. That will teach you to keep your mouth shut."-Ernest Hemmingway