You need to keep in mind that Racers have very fast metabolisms compared to most snakes so they'll need to eat medium sized meals two or three times a week. Snakes usually attain bulk once they hit their maximum size. Until then, all growth is put towards attaining length. Try and feed your racer rodents and maybe the occasional fish. Stay away from lizards and frogs-- they have huge amounts of parasites. Give him lots of space, lots of hides, and a good basking lamp and you'll be good to go.