I'm due to have my car re mapped tomorrow and I'm a little curious (basically want to know before I go) as to how this is done.

2.0 16v Vauxhall engine with 45mm throttle bodies.

Is this done in say 4th gear from low rev to 7k trimming the fuelling to suit ?

If so how accurate is the fuelling in the other gears.

How is the ignition advance determinned ?

The ECU senses load, low gears less load high gears more load
If mapped in lower gears you will notget a true bhp or torque that said the rolling road software is quite good at interpretting