I bought a Bama 4 bank chip which I am starting to regret. It is for a 2004 GT. I changed the gear and did a cat delete. So far it has not corrected my speedometer and the sensor light for the cat delete. When I called and complained they said it can take up to 50 or 100 miles for it to rewrite the computer. Is this correct? I am finding this hard to believe. Did I waste my money?