So, I ended up ordering a second stein mushroom muffler based on reviews saying it was "quiet" -
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1.
It looked identical to my Maxpower muffler, but I figured it was worth a try for $12. Result? Identical sound, within 1 dBa of the Maxpower. hahahaha
Pick for reference:
Oh well. I did notice a lot of the noise I was dealing with was rattling metal. I secured the hood, and it is now tolerable carting stuff around the property. So, I'm going to leave well enough alone for now.
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Current Fleet: 100, 126, 147, 128, 1450, 1650