The Koni SPA-1 series oil-filled shock absorber (for drag racing only) is a complete departure from the "90/10" thinking which is no longer effective in modern drag race competition. The old thinking was to allow the vehicle front end to rise quickly and stay there to promote as much weight transfer as possible to the rear wheels. This was achieved by virtually no rebound forces ("10") and a great deal of bump forces ("90"). This massive amount of bump force was supposed to hold the front suspension up to maintain that "bite." Only one problem. That nose-in-the-air attitude trapped huge volumes of air which ruined any attempt at aerodynamics so E.T.'s were not as good as they could have been. Koni SPA-1 series shocks deal with this in several ways. First, they use virtually no bump (compression) dampening. Why? To allow the front-end to settle quicker, restoring the nose down attitude that is so essential for cleaner air flow. Second, the rebound (extension) forces are velocity sensitive; that is, they increase at a rate directly proportionate to piston speed.