I have installed a bunch of different meth kits. By far the aquamist HFS are the best. They take a little longer to install, bc of all the wiring, but it is worth it. They work like a fuel injector. The system matches the pulse of the fuel injectors of the car. . Plus once you let out of the gas, they instantly stop spraying. That helps the stop the car from loading up on meth and possibly damaging the motor. Plus you can set up failsafes by using a mac valve, or an electric boost control.