If you have an S or an X model the a shorty or switch. Proper track tension Proper chain tension Clutch alignment Balancing clutches is worth it. 0 to 2000' ft above. Shorty or switch with a ripsaw or cobra, studs or no studs. 1.74 gear ratio, primary- 120 to 130 lbs rate spring, 70 gram weights(68 if your 275 lbs+) Secondary, 66/44.46 or 50/44full , 70 to 90 lbs rate spring. Shorty or switch with 1.5" + lug track. 1.81 or 1=86 gear ratio. Primary and secondary the same as above. As you see I just named the spring rate, that's because lower/ higher engagement and spring finish lbs can be changed for studs,no studs,1.25" lug or 1.5"+ lug. If you choose not to re gear, then none of what I said above will work for you .