400ex mods

[JeremyKS]

I currently have a R4 pipe but would like to get a header pipe too what works best. Also has anybody removed the screen on the r4 pipe and if so does it help. Also what all does removing the choke do does it help. If i was to drill some holes in the airbox lid would i need to rejet. Thanks in advance. Jeremy

[AtvMxRider]

If you have a stock motor you really don't need the headerpipe. Removing the chock gives a little better throttle response. some say they don't notice anything but some do(I did). If you drill holes in your airbox lid you will have to rejet. I hope a helped.

[4TraxRider]

If you remove the screen in the r4, it makes it noticably louder, but not that much difference in performance. It seems to rev a little more free and have a little more snap.

[northeast400]

I agree it gets a lot louder, sounds cool, not much more performance