It does sound a lot like a 2-stroke but that video doesn't really show the sound. If something gets too loud it make it into a garbled mess. It's definitely louder than I want it. I still need to put a spark arrestor in the muffler so I'm hoping that will dampen it a bit.
The gauge is the air-fuel ratio but since I was opening and closing the throttle it didn't sit in one spot. 14.5:1 is efficient but there's a peak torque somewhere around 13:1. I'm hoping to be able to dial it in that closely but when it's this far off it's hard to figure out which way to go.