Nothing earth shattering but put another 1.4 hours on the 13B homebuilt today.  After flying the 135 hp lycoming recently I was amazed at how quiet it was compared to the rotary.  Having read here about simply reducing the exhaust pipe after the Hush Power would give moderate noise reduction I had to try it.  First I installed a 2.5" to 2" reducer and flew for about an hour; it seemed a bit quieter but that could have been wishful perception.  Then I installed a 2" turn-down after the reducer, hoping that deflecting the exhaust down toward mother earth would give a marked improvement - couldn't tell any difference in the noise but monitoring the climb rate and engine rpm showed no measureable loss in performance.  For now it all stays in place and I'll continue to build time and think about insulation or sound barrier for days ahead.