Hi teckbot -- you have had good feedback about the burble from the 'masters'! In my experience, once that plug gap is sorted, a little midrange burbling is normal while breaking the engine in -- my club mates (very experienced gas engine flyers) all advised me to keep this setting for several tanks while breaking in, and I have only recently tuned it out. It took the tiniest screw driver width only on the LS needle and now is perfect. I was also new to this once and also overanalysed as you say, but this is what quality forum like this is all about -- being able to ask.