Richard,
Motor sounds good to me, is that the MA 20x10 if so you instinctively pulled the power back on the second pass on the downwind leg because you can hear the motor ripping the propeller. That's pretty normal for Master Airscrew propellers on a powerful motor they just dont hold their pitch well. I would seriously consider changing to a stiffer brand of propeller.

The WM Zero should weigh in at 17-19 lbs with retracts and flaps ? The 2.4 seems to pull just fine to me. Go arounds look ok, Accel and Decell sound ok on the downline. If your happy with the way if flys stay with what you have.

How's the sound meter, I had an old B&B muffler on mine at first and was way over the club limit of 99 DB at 10 Feet I was some where at 103. Changed to a slim line and three blade and got down to 99 fairly easily.

My LHS has a GS WM Zero on sale I may consider getting one after viewing this video.

Congratulations you got a keeper.

JDS