Well, here is my final update.
After experimenting with 4 sets of mufflers, what I found is that there are actually 4 phases, not 3. In order from quietest to loudest they are:
Phase 1 - Four 1/2" holes in front donut baffle plate
Phase 2 - Phase 1 plus drill out center rear baffle with 1-1/8" hole saw
Phase 3 - Drill out ONLY the front and rear center baffles - NO holes in front donut baffle plate.
Phase 4 - Phase 2 plus drill out the front center baffle (Four 1/2" holes in front donut baffle and remove front and rear center baffles.)
Phase 1 is a nice pleasant low tone, muffler. Louder than stock RK or RSV mufflers. (Of course your lawnmower is louder than stock RSV mufflers.)
Phase 2 is slightly louder than the Phase 1, mostly adding volume when under load.
The Phase 3 is only slightly louder than the Phase 2, with a slight more growl under load. Gives a little "bark" when you blip the throttle. I probably would not have noticed the difference between these and my Phase 2's if I hadn't been the one to change them out. (The Phase 3 is so close to the Phase 2, that for ease of modification, I would recommend simply doing the Phase 3 with the hole saw instead of fighting with drilling the 4 holes in the front donut baffle.)
The Phase 4 is slightly louder and has a lower tone than the Phase 3. It is, in my opinion a nicer sound than the Phase 3.
The difference between the Phase 3 and Phase 4 is that the four 1/2" holes allow more flow into the outside chamber giving it a lower tone. Same reason you get the lower tone when performing Phase 1.
The old Phase 3 is now Phase 4.
None of the above modifications are objectionable, and the wife says she can hear the radio fine at 15 at Phase 4 on the highway.
Even the Phase 4 is nowhere near a straight pipe or Screamin' Eagle, so you don't have to worry about waking up the neighbor's baby when you leave for work in the morning. But it is loud and "growly" enough for people to take a glance when you come down the road.
Each phase is only slightly louder than the previous phase, so if you decide to go up a phase, you won't have to worry about it being a significant jump that will deafen you. :D
Some have referred to a "puffiness" in the mufflers. I only noticed this in Phase 1, not in any of the subsequent phases.
Hope this is helpful.
Last update: 05:49 PM Thursday, June 2, 2005