A buddy of mine just bought a WB E series slip on pipe for his 02 Scrambler 500 and we need a starting point on the jetting. He is also going to run a uni filter so if anyone could help with a starting point that would be great. Even if you don't have the same pipe but just a slip on give what jets you are running. Thanks for your time and help.

 

160 is all you will need you could most likely get by with the stock 155 becusae they are a little rich from the factory this would be from 1500 feet to sea level you never said your altitude.
take it for a run if you are faster at 3/4 throttle than at full throttle you are lean on the main jet if you get a slight stumble at full throttle you are rich so go back one size on the jet .
if your stock jet is a 155 get a 170 ,165 ,160 they are cheap so what ever your stock size is get the 3 next larger that would be all you will need for jetting even with airbox modifications
Hope this helps. If ya need anymore help just let me know I have been through the whole thing before

 

Like Alpine said, they are rich from the factory, 160 will be plenty.

 

Thanks alot guys. This will help alot. Thanks again.