your gonna be unable to gear your medusa high enough to run well on 3s, you need atleast a 4s lipo to gear your 2200kv medusa motor right. with your 17t pinion and 46t spur gear and im assuming your buggy's diffs have a ratio of 4.3 you'll come out at 40mph with a 4s battery which is about the right speed that you want to gear for, semi pro suggested gearing slightly lower for smaller tracks, about 33mph, thats where your 13t pinion would work. You need 4s for these numbers to work out right. All i did to get this info is go to the sight me and semi pro suggested and input your numbers in there, its pretty self explanatory.