Like "RT" designations in the 70"s?
IMHO any increase in HP is a step in the right direction. A 650HP "Rod" can stiil beat MPG on a 130HP factory ride.
I've built/rebuilt them all.
The more HP/Torque you have the better the efficiency is. The more torque you have the better the engine/the better the MPG.
Look at the new GT 500... 600 something HP/580 something torque. 27MPG avg.
On the flip side I took a 3. whatever hp Kymco, and changed it to a 13/15/20 ?? ?? ?? hp kymco.
Mileage went fro 100MPG to 10MPG maybe! But if I baby it... and ride the OEM 35-40MPH? About the same MPG of 100.
Just sayin'