Excess heat is the #1 killer of transmissions. For individuals who tow, race or simply run their diesel hard, know that proper cooling of your transmission fluid is one of the most important things that you can do to increase the life of your transmission. When the mainline pressure is increased with things such as a high-performance transmission kit, you end up with additional heat being generated, so we recommend a Performance Transmission Cooler in such applications. PPE's Performance Transmission Cooler is a direct bolt-on replacement part that lowers the fluid temperatures up to an additional 20 to 30 degrees over the stock unit.