I used it today it was nice I still am not 100% sure what I am looking for..... My wide band said 13.5-13 wot but I see no fuel ring in the bottom. I can kind of spot it. It did help me spot some very small aluminum speck on the electrode and the ceramic I let out 3 degrees timing in some spots and it cleared up.
Then his pos plug wires broke tying to pull them off so we fixed that and I didn’t want to pull any wires again (we where out east in the middle of no where) I also had dyno time lined up to try to get into some real tuning but that fell threw due to no money for it.................
All and all a good day tuning
I think it was worth the 30
I too would like to see a good write up with picks maybe done by some one at this site because I can trust it. There is so much crap on line about reading plugs it is out of hand.