Linear mapping does what it says: mapping is a straight line. But it's talking about the JB4's mapping.
Normally pedal mapping isn't quite straight, depending on how the OE set up the ECU. The JB4 does not change the pedal mapping - it can't. All it does is change the pressure sensor readings back to the ECU to goof the ECU into giving the engine more boost (and more or less fuel) than the ECU actually intended.
Adding the OBD2 connection lets the JB4 read data off the bus, such as pedal position, so it has a better idea of what you're doing instead of just reading the MAP/TMAP pressures. This lets the unit have a bit more finess in its response - more pedal = more boost, while also taking into account what the pressure sensors are saying.
My *assumption* is Burger spent some time trying to make the response curve match the OE pedal curve (whatever it is). The difference will be in the middle - not on the ends. And the difference is probably subtle.
And if you're really running map 0 like your signature says, then the JB4 isn't actually doing *anything*.
If you really want to change pedal response then you'll need an ECU tune. And specifically you'll need a custom tune because the normal aftermarket response is MORE THROTTLE NOW!
There's one pedal tuner that has a slower curve (rather than just faster curves), but it probably still won't do what you want.
You'd have to sweet talk Burger into making a custom map for you. Even then, the problem is all the JB4 can change is the pressures. So sure, it could build less boost until later in the pedal, but all the other tuning (TCU settings, the rest of the engine settings, etc) are still thinking it's PARTY TIME.
