Years ago..Before electronics became the norm for slowing cars down. A guy that raced SC with an injected altered used the bolt under the pedal...each turn was worth @ .007 in time...Seemed to work well for him.. Another guy that ran S/ST ran a BBF with 2 vac. carbs on it. He drilled holes in the vac rods and would put clips in a hole to limit how much secondary the car would see... both are examples of limiting the total throttle the motor would see