What I use to do is start with a low advance timing map and start raising it up top, I can always look for knock in my datalogs and I know when to stop raising. Sad thing is I haven't done it yet in my car, I could even hear knock at least 2 times across the band, If I hear some knock it means I do have a lot of knocks. I think I'll take a couple of degrees from the base timing just as long as I have the time to do the tuning