I have been searching for the "bucket RPM" of this motor...
I.e. "I'm low on fuel and I need max range RPM for 5th gear"
It's somewhere between 2300 and 2800.
If I should cruise at 85+ (ha!) my mileage goes down to low/mid thirties also.
I don't have any data for sustained ops at 4000 RPM although that would make for an interesting data gathering expedition....hmmmm.