I have always run the upper hole on my Cuda, and it hits like a ladder bar car with a 1.38 60ft. No wind up like a typical SS sprung car, and then launch, it just hits....Never tried the lower hole, but as stated, all the fast leaf sprung cars are in the upper....I run just a slight amount of preload with my weight in the seat. Street driven and raced, with no changes and I like them.