because it's just easier and more convenient to use a boost controller. I can't guess how much boost to run for each gear. It just adds more dyno time needed to get everything dialed right. Also I like the little boost control and the display and the control knobs are all right there. I don't care to carry the laptop to the car every time and check and adjust from it. I have had the Haltech for many years. I don't get excited anymore to see the laptop screen. I now just want to turn on the car and drive.