hmm, well before you go messing with your knock sensors i would bump that mix up to 30% and try it again just to make 100% sure. you dont want to ignor real knock.

as far as desensatizing your knock sensors, you can buy a knock out box, i am not 100% sure what parts are in there but people that have them say they work. i did somehting very simple, put 1 10k resistor inline with each knock sensor wire, i have no codes, no false knock and still see knock when it is real. cost about $1 or so. i have been told doing it this way will set a code but it hasn't on my set up and they have been in for months.

i had a ton of parts on my truck and couldn't do any better than a high 14 because of KR, once i got the false knock taken care of i droped to a low 13 and broke my tranny within a week. my timing went from negative numbers up to 14deg's. having KR pulls timing from your regular timing also so if you see 6deg it might be alot more than that. it might have all ready pulled 6deg(knock learn) because it has learned it needs to and then is actively pulling another 6deg(knock retard)