The previous owner of my car (96 mustang gt) claims it had a flash tune but misplaced the handheld tuner (weather its true I don't know) anyway... I'm looking at having a SCT 4 bank switch chip tuned and install it in my car. Nmy question is, will the new tune on the chip just build on top of the flashed tune or does it ignore the flashed tune alltogether and the chip takes full control?
Like if the flashed tune was adding 4 degrees timing over stock and I plug in the chip and its adding 3 degrees would it now be 7 or would the chip ignore the flashed tune and it would only be 3 degrees? Thanks in advance.

 

The chip will take control.

 

Awesome, thanks for the reply!