Need advice for slowing my car down consistently.

Years ago a friend of mine wanted to do the same thing, but at the track to run two different classes. We came up with a quick solution. Duct taped a half inch drive one inch socket under the pedal. He was dead on consistant all day. Not exactly the perfect way of doing things, but in a pinch it worked good. Like a throttle stop. He staged the car the same and throttled it the same but with the socket there it stayed consistant. That day he got runner up in the slower class and went 4 rounds in the fast class. Simple, yes and it worked. Costs nothing.