I recently bought a 2007 GT that had some mods. These mods where removed to pass emission testing. The CPU was reset to Ford specs, however I notice the speedometer is off by 10mph. I have heard of an engineer mode that might calibrate the speedometer, anyone know how to access this mode? Also the heater works great, but in defrost mode no air comes through the vents toward windshield.

 

Never heard of an engineer mode. If you have a handheld tuner (SCT, diablosport, etc) you should be able to set the wheel size when you flash a different tune. If you're talking about just while you're in stock form, I always thought a dealer had to reprogram the ECU