WIP BOOST Engine Performance

Hi,

How to BOOST the speed max, by changing the gearbox settings or the torque, I don't know !!!
I wish someone answer me.
Thanks PLS.

 

Adjust gear ratio

 

Thanks I change

Code:

"gearRatios": [ -3.89, 0, 4.20, 3.49, 3.66, 3.24, 3.0, 3.0, 3.0 ]
to
 "gearRatios": [ -3.89, 0, 0.5, 1.2, 2.2, 3.2, 4.2, 5.2, 6.2],

The speed is 474 km/h before get in the air.