Does KR have any effect on MPG? I may be seeing a few degrees of KR, as I have a 3.4" pulley on very few mods. The DP is next, for a bit of KR reducing. Just wondering what the thoughts are from the experts.

Well your engine isn't putting out as much power per revolution, so it'* less effiecient. Anything that robs power with the same fuel consumption per cycle will take away from MPG.

Since you only really get KR when driving hard, I don't think you have to worry about milage in this case.

You should have a 180 t-stat and 1 heat range colder plugs. NGK TR55 gapped at .55 should do the trick.

I agree with Sol. KR is only going to happen when you put your foot down, and when that happens with or without KR your mileage is in the single digits.

Me 3