You can not forget the most important factor of stock racing....corner speed. Your car has to rotate through the corners with little to no effort. You DON'T want the car to be too loose as you need to be aggressive as well. Hard to explain in a short paragraph but once you get the car handling well enough to carve the corners without loosing any momentum you will pick up a lot of time.

Also the stock motors work better with more run time on them imho. A few com drops also help.

Bob