IDC dropped when I went to 80's. Nothing theoretical about it. 50's, 60's and 80's were new when I bought them. Anyone that knows me knows I always go above and beyond for fueling and going over every run on PL for anomalies. Eric mentioned on his website years ago that 60's and race gas would get you close to a mid 10 horsepower level. I have this habit of listening to the very best.