There are a handful of pilots who fly over my house with prop tips going near-supersonic. It makes a dreadful racket, much louder than other aircraft. There are times when I'm tempted to get the handheld and tell them to slow the &&(*$ prop down.
Most planes spin the prop at 2400 or 2500 rpm. The noisy ones spin at 2700. The difference is small but enough to make a big difference to the shock waves coming off the tips.
If your Maule spins at 2700, I'd suggest using 2500 unless you absolutely need every last HP - which in a Maule I imagine would mean if you want to take off in less than the length of the aircraft.
Anyway it's easy enough to figure out the tip speed - πrΩ and all that.