We use the A/F gauge that came with our Dyno-Jet chassis dyno. It was reading fine, around 11.7 untill it got to 4600. Then it started it's climb upward to 13.6 at 5700 where we lifted. We didn't want to spin it up any farther untill we got the fuel situation straightened out. Don't want Ray to have to put new pistons in his Bullitt too early, you know. Waiting on our boy over at Superchip to get a new program done right now. As soon as he gets back to me, we'll download the new program, and get a few more pulls in on the dyno. Still plenty of room left to make some more power. I'll try and keep you posted.