Must upgrades are servo horn (25t hot bodies), 12mm alum hex's of course and if your not afraid of a little dremel work the serpent hard servo saver spring works wonders with a good servo (just have to increase the ID on the al nut end). The stock saver spring is too weak. And of course springs as Cain mentions. Your choice on springs I buy what is locally available so went with kyosho, but had some xray progressives to try as well.