Pmed.
Thanks bro for the feedback, here is some explanations:

From my own experience on my car, after adding the VS, acceleration and torque increased quite a lot, i was happy about this and enjoying the reving up every time i drive (Due to the smoothes and better acceleration, so like to rev more comparing to before installed the VS). From this driving behavior, my FC increased. Well the driving behavior has been changed after installed the VS, where more energy is using to move and accelerate the car coz i press the pedal harder.

Then i decided to change the driving behavior by pressing the pedal lighter where the acceleration up is roughly same as before VS (But now added smoother and lighter pedal pressing) and the result speed also same as before VS, then i get about 50KM extra for town and highway drive mix, and around 80 KM extra for pure highway drive.

The theory here is before VS, the force you press on pedal doesn't result in proper outcome (Engine power) meaning that you press harder the engine will still not going much. However after VS installed, the more you press the more the engine will have power to go then the FC will increase of course or else it doesn't follow the rule of energy.

Pressing pedal lighter will still gaining the same output as before VS, thus in this way your will see lower FC.

Try to drive on pure highway like 1 trip to ipoh or penang.
Pmed.