Need more info,,, where do you ride most? Trails or mountains? Is it a 2" track or 1.5". If you plan to ride both trails and mountains you will have to sacrifice speed at least. What type of snow do you ride, fluffy powder or semi wet to wet? Knowing cat the f6 is probably geared a little high, throw in the longer track which will add more drag, put hyperfax on this will help the drag. Without knowing a relative top speed of your sled it's hard too say where the gearing should be. Some will say that all you need is clutching and or stiffer springs I disagree, especially with what was once a trail sled. Is this sled equipped with a chain case or gear drive? If it's a chain case try 19 43 gearing. If you can get a polaris hyvo gear and chain set this is tougher. If it's a gear drive, depending on what is stock try 57 63 or 55 64 s these seem to work in an 800 motor. I don't know it all but when it comes to performance through gearing most of the time lower is better. Does this answer your question???