While the 4L80E shares several of the heavy duty components that are used in the TH400, there are still plenty of parts that benefit from an upgrade through TCI. One of the first is the clutch packs. Instead of the standard "brown" friction clutches, TCI uses "red" heavy duty clutches. The red friction material can take substantially more torque and horsepower than the standard material. Along with the clutches, TCI transmissions also get nitride steel plates.