Not that I know of, on both counts unfortunately.
(The rest of this is speculation, so make of it what you will)
This is because of the way GP4 enforces the rev limit; rather than being a single hard limit, it has three limits.
This can be seen in a GPxSet.log file, after using a physics set.
Patching max RPM1 from 16600.000000 to 15000.000000
Patching max RPM2 from 16800.000000 to 15180.722656
Patching max RPM3 from 17000.000000 to 15361.445313
So, while my physics file is limited to 15k RPM, the actual maximum RPM is 15361 RPM.
My guess is that the AI are bound by the 'max RPM1', and the human player is not.
F1 Graphics Swapper ---
Lensdump - Renders and Screenshots ---
GP4 Performance Generator