Maybe it’s the gasoline around here but I find that my 5.9 just simply likes the 89 octane and hates the 87. The curve on the distributor is hot rod like. Not to quick. For me, it is what it is. But when I go out of state, it is fine on 87.
I do favor the LA for intake choices and the verify of available parts. Ether way you go, 20+ mpg’s should be obtained.
