OK - so I re-tuned the 26cc Gasser (SV) and it no longer dies when the throttle is cut back to idle at the top of a hammerhead.
But, it now pops and sputters - but only when flying upright and level.
When I fly it inverted or in a knife edge - the motor runs and sounds GREAT.
Any ideas on why it is popping when gurgling when flying level?

sound like running rich on hi side

ditto.........try leaning it out on top end alittle at a time. and see what happens. maybe 1/8 of a turn at a time, but don't go to much or you'll get her to lean. punch her full on the ground each time and make sure it transitions good, before taking her up.............GOOD LUCK........RON

I don't know guys - It seems like we peaked it out already - but, its worth a try.
Why would it run great inverted and in a knife edge but pop while flying level if it is too rich on the high end? I don't understand the difference - can someone explain the difference to me?

One point brought forth is that you just move the needle a very small amount at a time and then see what happens.

Just a little tweak. One notch.

Have you tried putting a carb static vent tube to inside the fuse.