Hi Scott

You bring up a lot of excellent points and have some good data.  That brings
up a lot of questions:

1.    Did you stick the dB meter all around the plane to see where the other
noise leaks were?  Like how is the back of the firewall at the penetrations?

2.    That's interesting about the baggage compartment.  It was one area I
suspected and was going to test.  So did you try adding insulation there to
the bulkhead or just test it with and without it being installed? And how
well does it fit around the edges? A LOT of noise can escape through a VERY
small gap.  

3.    Did you check around the canopy for air coming under the frame, around
the hinges, etc?  A lot of noise is aerodynamic and is from boudary layer
buffeting.  It is often the dominant noise factor in large jets.

4.    When you did your testing, was the noise meter set to dB "A" scale or
"C" scale?

5.    Excellent observation on the air vents.  What was the open and closed
vent readings?

6.    Do you know what the weight of your insulation kit was?

Thanks again for the info!

Dan