Finally a heavy duty fan upgrade option for Trailblazers! This kit includes two high flow 12 inch spal fans and a custom shroud to mount them using factory mount points. No drilling or cutting needed. This conversion eliminates the power robbing stock electro-viscous fan and replaces it with two high flow computer controlled electric fans perfect. Each fan is independently controlled by the PCM. This conversion has been credited with gains ranging from 12-18 RWHP and fuel economy improvements of around 1 MPG. See these fans in action! See these fans in action!