Turbo City uses a GM ECU for reliability, durability, and programmability. Turbo City has off-the-shelf, basic PROM chips calibrated to run well in most applications. Each EFI package has a PROM tuned for the vehicle requirements based on application, gearing, and other specifics provided by the customer. Fine-tuning can be done with a call or two, or you can take your truck to Turbo City in Orange, California. The ECU should be mounted in a dry location. We chose to mount it in the glovebox.