I'm having difficulty getting the pictures attached so I will forge ahead without them for now.  I attached the test rig to the airbox outlet and used  a large ShopVac to pull air through the airbox.  I measured differential across the airbox with the manometer.

Bone stock: 9.25"

Stock configuration with K&N gauze element: 8.00"

Snorkel removed (loud): 7.75"

Plastic airbox cover & decorative tin removed (too loud): 5.25"

Plastic airbox cover removed, tin replaced (too loud): 5.50"  

Snorkel back in, 1.75" hole in plastic airbox cover, tin on (loud): 6.75"

Plastic airbox cover with 1.75" hole and baffle (sounds stock): 7.25"

Oval slot .37" x 2.0" cut in left side of airbox (sounds stock): 7.00"

Two foam blocks removed from underside of seat: 6.5"

Results: the noisy mods (K&N filter, plastic cover removed, tin cover in place) offer the optimum improvement, 3.75" less than a stock configuration, but make what I consider to be too much noise.  The quiet mods (K&N filter, hole in plastic cover, baffle, oval slot left side, foam blocks removed from seat) offer a decent improvement, 2.75" less than stock configuration, with no discernable increase in noise.

I will do my best to get pics of the mods posted.

Here is a picture of the baffle installation.

Here is a picture of the foam blocks to remove from under the seat.  The picture only shows one removed, the one on the opposite side of the seat is still in place.  If you go slow, they come off easily and remain in tact so you can reinstall later if you like.

I hope this post provides some useful data for anyone looking for a breath of fresh air.

Oooops!  The site just won't let me attach this picture.  I guess some of my photos exceed the file size limit (even though when I check the properties of the file it shows less than 2048KB).  So let's try a verbal description.  There are foam blocks attached to the underside of the seat with double backed adhesive tape.  I removed the two blocks running fore & aft that are located just in front of the hard rubber pads that carry the weight of the rider.

OK.  That seemed to work.  Here is a shot of the rig installed on the airbox.  It actually fits quite nicely.

Best regards to all.

Flow is pretty simple to calculate.  The equation is Displacement in CID x RPM / 3456. That is assuming 100% volumetric efficiency. For most street engines, about 80% is close. So for a Savage at 6500 rpm that would be 40x6500/3456=75 cfm. 80% of that would be about 60 cfm then.

A typical industrial vacuum like what you would find at a car wash is rated at 100 cfm. So his shop vac test is in line with the airflow of the engine.

  Peak EV for any motor only occurs at peak torque (3400 rpm for a stock LS650) .Before 3400 you have reversion in the intake ,after peak torque not all the exhaust gases leave the cylinder.

    652x3400 /3456=641

        641/652=98.27% EV (in a perfect world)

Regarding Dave's comment: wonder how vacuum noise relates to engine intake noise.  I'm not sure I understand the question but I will try to provide an explanation.  My comments regarding noise were based on the noise level I heard with the engine running, not the vacuum cleaner.  I would install the mod and run the engine.  It was strictly my opinion based on what I heard with my ears.  I wish I had some sort of sound measuring instrument.  If it was hands down louder I defined the result as "loud", if it was obnoxious I defined it as "too loud", if it was a close call I would do several iterations with and without the mod until I felt comfortable with my final opinion of the sound level.

Regarding Dave's comment about the seat foam:  I could actually watch the column drop in the manometer as I lifted the seat off with the test in progress.  The foam blocks form a channel that guides the air in from the rear of the seat down to the snorkel.  I'm pretty sure they are for noise mitigation.  Taking those two out didn't seem to affect noise much.  The rear foam blocks are a bit larger, but I didn't mess with them because I was able to achieve a reduction equal to total seat removal by just taking out the forward foam blocks.

Regarding comments on the ShopVac cfm:  I used a 5.5 Hp vacuum rated at 140 cfm so I knew it would be a torture test.  To amp it up a bit more, I removed the vacuum cleaner's filter so it was probably capable of moving more that 140 cfm.

Regarding justin O guy 2 comment about airbox volume: I don't believe I changed the airbox volume appreciably.

Regarding comments about resonance, reversion, etc.  Fast650 has it exactly right, I was simply doing a comparison.  I deem these modifications successful.  The stock airbox restriction to flow has been significantly reduced without any noticeable increase in noise.  This modified airbox will support higher airflows required by other mods like increased displacement, better exhaust systems, better flowing carburetors, head mods, etc.  Will it fully support any and all mods?  Don't know, but it will definitely do better than the stock box.

The testing I performed provides some concrete data.  I know it's not very sophisticated but it's good solid data.  To me, it's better than making a change and going for a ride to see if it works.  Of course, the proof is always in the pudding.  It's a beautiful sunny day here on Oahu.  Perfect conditions for a little test-n-tune.  I will let you all know how it works.