On my 04 Pro X 700 when you turn the key it can be on regular or it can be on prem. what is prem??? any one know what the difference is?

You set the ignition switch according to the fuel you are running in the sled. Regular or Premium.

This changes the amount of spark advance delivered by the ignition system. It allows improved power and economy when you are running Premium octane fuel.

When ever i fill up i get the expensive stuff it has the highest octane rating but is that considered premium or would premium mean race fuel??

The "prem" on the switch refers to premium at the pump, NOT race fuel. Typically, the highest octane at the pump is refered to as either supreme, super, premium, etc... depending on where you are getting the fuel.

Polaris considers fuel with an octane rating of 91 or higher to be premium fuel.

the ON/PREM position will also turn on the "Premium Fuel" light.

Thanks alot, Im going riding tomorrow all day and ill make sure to put it on premium now because that is all I use.