The Trans-Scat Valve Body Kit was designed to deliver a good solid shift suitable for towing applications or a competition quality gear shift by eliminating transmission slippage and lag. This provides a harder more positive shift and allows you to downshift the vehicle on demand. With most models you are able to manually shift and hold the transmission in first gear until you shift to a higher gear which is very advantageous when extra power is needed to top a hill. As long as the vehicle remains in drive it will still be fully automatic.