The Blixxton-Mack module is designed for the 1991-1997 Mack VMAC I & II engines. It takes only a matter of minutes to install it into the existing wiring harness under the hood. It has a 3 position switch, allowing the operator to toggle between stock, 15 percent, and 25 percent horsepower increases. It brings alive the E7 300, 350, and 400 horsepower engines. Due to injection pump limitations it offers no benefit to the VMAC II 427HP or 454HP engines.