103's will help get rid of more kr they are a pretty cold plug. You want the hottest strongest flame possible in the cylinder, so when you use the 103's they're to cold. I would use the 104's for that setup, maybe if you made over 300whp i would use 103's but you shouldn't have to go through that much to get rid of the knock you're having. Not to many enthusiasts care to much about gas mileage, which is a good thing lol, i know i sure the hell don't. I get like 15mpg's on a good tank of city, and 20ish on a good tank of highway. For e85 that's not bad IMO. I guess it really doesn't matter what plugs you run, maybe stick with the 103's because of the knock you can't seem to get rid of.
