What is the best rpm to change up during fast driving?

Depends if you're a power person or a torque person. I would chose a shade of 4k rpm (where peak power is developed)....

Chris

Yeah.. ive found 4k to be about right.

a bit under 4000rpm perhaps, so that when you change up you are back into peak torque. I can't remember!

And at what revs to change if you want fastest acceleration?

About 4200-4300?

Keep looking out rear view mirror.

Change when black smoke starts to cause hazard to other motorists...

Keep looking out rear view mirror.

Change when black smoke starts to cause hazard to other motorists...

Best leave it in neutral then.

I only notice smoke when low down (1500-1800) and never higher up in the rev range (1800-4000)

i'd say 4k too