The Holley HP and Dominator EFI Systems are in a class of their own. The HP System is a plug-and-play alternative for your stock or built late model factory EFI engine. The HP EFI ECI and harness kits are designed to be used with popular factory EFI engines as an alternative to the factory ECU and harness. The HP allows you to accurately control the fuel and ignition of your engine along with additional controls for nitrous and forced injunction or water meth. The Dominator System can do all the functions above including control a 4L60E transmission as well as the fuel and spark on your street rod. There are also enough inputs and outputs to allow the Dominator to serve as their own data acquisition and control module. NOTE: You have to purchase all wire harnesses for the Dominator individually to complete installation.