gearing simply comes down to what your doing with the sled, if you do alot of deep snow riding youll want lower gearing, if you do more groomed trail higher speed riding youll want taller gearing. Anytime you rev a engine higher you automaticly gear the sled up taller without touching the gears, so for example if you have stock 22/38 viper gears and then rev the engine to the cpr pipes of 9200rpm, your already geared taller then the 22/38 is because the engine is over revving and making the gearing taller.
gear the sled for the riding you do 90% of the time. Decide what your top speed is and gear accordingly. Lower gearing makes the sled more snappy and quicker in a short run due to the torq. multipulcation,but it also doesnt keep the belt in a more efficient 1;1 ratio depending on how far you push the mph achieved as the belt will go into overdrive.
I like to keep the top sprocket as large as I can and still achieve the ratio i want to run for the mph I intend to run 90% of the time I ride.