I definitely agree with hav_lova. This year I started breaking down my car after every 2 to 3 weekend runs to check for worn/ damaged parts and cleaning my (stock) bearings rigorously and just that made me a more consistent driver week to week. Also, the transmission was just as smoothe as my friends car who went out and bought Ceramic bearings. Don't waste your money unless you make money racing these cars.
good luck