they must ,thats what the stickers said.lol
ran mine again today ,according to the eco guage my most economical speed is 3500 rpm which is 37mph using 1.9 ltr per nm,the guage actually reads 2.1 nm per gallon.its a pretty comfortable cruise speed,it was still 2nm per gallon at 4000rpm 42 mph.im expecting better with the 3 blade props,still pretty good for the speed its doing.