You can notice a shuddering torque converter under throttle at low speeds and also under heavy throttle with high power engines. The kit's function is to increase the transmission line pressure when the lock-up clutch is engaged. The PressureLoc cylinder rotates the transmission's throttle valve shaft to simulate 3/4 throttle travel to increase the line pressure to 90% of what the valve body design can attain at wide open throttle. The resulting pressure must be measured and set when the kit is installed. The PressureLoc is primarily designed for stock or mildly modified engine applications and owners who have installed an exhaust brake and want some extra protection. It is not a replacement for a modified valve body! High horsepower and heavy-loaded applications should also be equipped with a BD Valve Body with larger porting for pressures up to 180psi. The PressureLoc increases the clutch applied pressure to 90% of what the valve body is capable of achieving at full throttle when you are only at 1/4 to 3/4 throttle travel. This kit addresses the need for more clutch holding pressure.