Rico the throttle curve you gave us, is that for idle up ? Can I ask where did you get that info ? just curious.. as usually the throttle curves are a much shallower V curve on Idle up and normal more is straight line. If you need help with that, please let me know.
Motor is a 3800KV motor. Looking at the specs, the battries you are using are a bit lower power than what a 450 would make good power with. The motor can pull a max of 36A and your battery can provide a max burst of 20A. There is a definite mis match there. Depending on your flying, you can get away hovering and puttering around with these batteries, but I would be careful going any harder on these batteries, as they will not be able to supply the amperage the motor needs. If you are just in a hovering stage, they are just fine.
RPM:
(3800KV (motor KV) * 12.6V (full battery) * 0.8 (motor efficiency) ) / Gear ratio = head speed at full battery (at 100percent throttle)
(3800KV (motor KV) * 11.4V (recommended voltage of used battery) * 0.8 (motor efficiency) ) / Gear ratio = head speed at end of flight (at 100percent throttle)
Gear ratio is main gear count/ pinion
So that puts your Headspeed at :
Full battery: 38304/13.63 = 2808rpm
end of battery : 34656 / 13.63 = 2541rpm
That is at full throttle .. so if you run 60 percent throttle just multiply by 0.6 and thats your headpspeed (average)
at this point with the 20C packs, to make them not stress too much 11t is good. But if you get higher rated batteryes (35C or so) you might be able to get more power and headspeed out of them.. and they will be able to handle 12t pinion.