Do yourself a favor: muff mod and tune it. Grab a fine thread sheetrock screw and screw it into the red plastic h adjuster on the carb. Don’t worry about changing the setting. Just thread it right in and keep turning, the red plastic lock will push up against the small aluminum frame that captures the locks. Pops right out and no damage to the carb. Now you can fully adjust the carb. Keep the 2 red plastic locks and the aluminum frame in case of warranty.
The muffler is just as easy: take the screws out of the muffler deflector, remove it and have a look. Several ways to mod that, so I’ll leave it to you to decide. Again, super simple.