EFI is a customized tune with parameters changed through the computer. Tuners such as Kory Willis, Idaho Rob, etc have years of experience and have tunes made for you and you just flash them onto your truck. Better mileage, power, and cleaner.
Don't forget tuning from this guy ^^^ he has been in it for years and is a vendor here as well. I can attest as a tuner to saying his tunes run great too!
I bought a 2003 HD Silverdao with 5 inch MBRP exaust with tranny built for 50 hp? But what I have been told, nobody knows where the tuner went and cant get passed vin lock , having it worked on and shop says they cant get into system it is vin locked, what can I do to bypass this or flash system????