The CAT4500 performance Module is designed for all the C6.6 Caterpillar and Perkins with common rails fuel systems. It can increase horsepower up to 30% and decrease fuel consumption by 10% to 20%. You can adjust the power of the module from stock to +15% to 30% with a three position switch. The CAT4500 fits on the following applications : Caterpillar: MT475B Challenger, MT515D Challenger, MT525B Challenger, MT525D Challenger, MT535B Challenger, MT535D Challenger, …