-------------- Original message from "Mark Steitle" <msteitle@gmail.com>: --------------

For rotorheads that are contemplating using (also the mildly curious) the Flowmaster HP-2 "resonator" muffler,

I installed the HP-2 today on my 20B and was able to do a run-up.  Bobby Hughes and I both agree that the exhaust tone is much, much mellower with a deeper tone.  My Lighspeed ANR headset had no problem cancelling out this low-frequency exhaust tone.  While the overall sound level was still pretty significant, the exhaust tone was much more pleasant to the ears.  The ear-piercing, glass shattering, nails-on-the-chalkboard, make-you-bleed-from-the-ears, exhaust tone is totally tamed.  The 3-blade M/T prop is the primary noisemaker now.  The test took place between two rows of hangars, so I feel that DB readings are not very realistic.  I'll take those again out on the ramp and post the numbers.  If the HP-2 holds up to the pounding of the rotary's exhaust, I'll be a very happy camper.

Mark S.