You need to edit the vehicle handling to make it more powerful https://wiki.rage.mp/index.php?title=Vehicle::setHandling
for example
mp.players.local.vehicle.setHandling("FINITIALDRIVEFORCE", 10.0)
mp.players.local.vehicle.setHandling("FTRACTIONCURVEMAX", 5.0)
mp.players.local.vehicle.setMaxSpeed(10000.0);