Jetting on my freinds Z400

[Tramatized]

My buddy seems to be having jet problems.........he recently put a hmf slip on and k&n air filter with the airbox lid off............what should he have this bike jetted at? it runs good it just has some issues in high revs.........my buddies warrior beat him in a drag race so i know its not running how it should be.......especially since my freind with the z is far far more experienced with riding in general and drag racing

[nos455]

I have a 04 z400 with a slip on and a spetra filter I'm running a 145 main jet my lid is on but there are 3 . 1 inch holes in the lid.. it seems to be good it doe'nt load up or bogg at any rpm in the woods or track ..