So again it's my gearbox madness, the agression factor i find to be a little temperemantal when it comes to large diesel engines (like the one in the bus) as it doesn't use all available torque... but it's quite hard to use the non agression gearbox in current state, you have around 15% throttle difference between all guns blazing full rpm, and leisurely early upshifts (like 1200rpm! -i could increase this sure, but then it doesn't feel right at low throttle openings) so on a hill you can be hunting gears quite a lot!
No, sorry, with stock code it's either throttle^3 or the smart stuff. You'd have to run your own code for this.