IMO I would keep the Medusa and run it on 4s lipo if you want something crazy, I have a VXL Rustler with a Feigao 9L with 4s and it kicks ass, my 9L has a lower kv than your Medusa at 2700 . I run MOD 1 gearing using a Revo 40 tooth spur with a 16 tooth pinion