Dave, I guess the butterfly valve is an option.  The Fastman also suggested that.  However, I want the thing quiet at WOT too.  In fact, WOT is where I really want it quiet.  The last thing I want is to attract attention when I'm havin fun.  Who knows, at some point I may have to relent if I want the best performance.

Armen, I think you will regret the auxilliary baffle.  The Mac core is already a bit small.  Once you but an additional baffle in there the restriction will go through the roof.  I'm planning on an attempt at packing the Mac.  I have some ceramic wool that I want to try.  I think I might be able to cut the muffler open and pack the area surrounding the core with that ceramic wool.  I think that might reduce the high frequency noise.  It will still be loud, but not so grating and obnoxious.  Check out this video.  It demonstrates how effective a combined approach is.  The Mac uses restriction and small directional changes to scrub off the acoustic energy.  Listen to what happens when I augment that with the glass packing (absorption).

https://www.youtube.com/watch?v=_U91BRWUc6s

Amazing isn't it.

Lancer, I have old test data from May of 2018 where I used one 5.5 HP shop vac to test several mufflers.  It was a different rig but I really can't imagine the rig would make much (if any) difference for this sort of test.  With a single shop vac, the unmodified stock muffler pulled 35" H2O, the Dyna pulled 27.5" H2O, a Herritage muffler (non-catalyzed) pulled 31" H2O, and a SuperTrapp with 21 discs pulled 13" H2O.

Regarding your question about where the manometer was tied in.  The manometer is connected to the 4" ABS pipe.  So the shop vacs tie in at the bottom, the manometer ties in at the center, and the muffler sits on top.  The manometer reading is the difference between the two legs.  If one side goes up 10", the other side goes down 10", so total difference is 20" H2O.

I marked up this picture in red so you can see where the manometer ties into the rig.

Amazing write-up, as per usual. Based on your review, the C-bomb w/baffle would be the winner for me. I like the look and prefer a bit of a growl in the exhaust note. Plus it also shaved a few pounds. Maybe I'll give it a go myself instead of saving for a supertrap. The supertrap although it has adjustability, seems a bit expensive. I've been struggling with the cost as it goes against the principal of the Savage for me.

I'm guessing it's a fairly easy endeavor to fabricate your own baffle? Just search around YouTube and I'm set?

DBM , If you didn’t build motorcycles you could have been an excellent

MAD Scientist  !?

LOL

"MAD", of course.  "Scientists", not so much.  

Verslagen, great suggestion on the decimeter.  I love it.  I was able to find a free NIOSH app for my iPad.  I used it to take some readings with several of the mufflers installed.  It was informative.

These readings were taken with my garage door closed, bike sitting upright, iPad resting on the seat (same orientation for all mufflers).  Took readings at 1300 rpm/3000 rpm/4000 rpm.

LCGP with 1.5" baffle:      67/77/81

LCGP with 1.75" baffle:      69/79/81

Mac (chrome) :      70/83/86

Mac (black):             73/82/86

Mac (black) with packing:  70/80/83

C-Bomb with baffle:  64/78/81

C-Bomb no baffle:     71/83/85

Stock (modified):      63/80/82

If you compare these levels to NIOSH guidelines for noise exposure, it's pretty evident that the app isn't accurate.  There's no way that NIOSH would permit unprotected exposure to any of these mufflers at 4000 rpm, so I suspect the actual noise levels are significantly higher.  But the app is a great tool for comparison.

The federal standard for the Dyna & Stock mufflers is 80 dB but I don't know what the test parameters are.  

I believe that any recording, video or sound reading using a phone or video camera is pretty useless.  The microphones on these little devices are made to record normal sounds, and loud sounds are clipped and made to sound "less loud" than they really are.  If you doubt this just go listen to a recording of a "Top Fuel" dragster on YouTube.....the darn things take your breath away in person - but on the video they are no louder than a recording of any other engine with a loud muffler.

I also believe that the sound of an engine "with full throttle and under load" is significantly louder than when it is revved up without any load applied.

When my wife and I went to TN/NC one fall to see the colors and do some hiking, we walked on a trail at the Cherohala Skyway.  We had walked about 30 minutes away from the road, and we could still hear the big V-Twins with open pipes - some of the really loud ones we could hear for 15 minutes as the noise just echoed down the valleys.  There really should be an enforced "maximum" sound value on public roads......just as there should also be a "maximum" applied to the brightness of the added headlights (some of these fellows also install 5 or 6 LED headlights on their bikes).

If you really want to record the db values I think you need a sound meter - but since the loudness numbers really don't mean much to us I am not sure if it is any more informative than your "opinion".  Most of the people who have installed a MAC muffler on a Savage have removed them as they are just too loud......unless you are a hard core noise maker!

I know this varies state by state but an HP officer told me the decibel level is measured 25’ from and at a 45^ angle from the rear of the bike, out in the open, with the engine at idle.
I think that was in SC .

11/22/20

While I am waiting for materials to enlarge the baffle tube on the LCGP muffler, I decided to try and quiet down the Mac muffler.  I have two, a chrome one and a black one.  Since the mods I was planning require that the muffler be cut open, I decided to work on the black Mac.  I can’t touch up chrome with paint.

I wanted to make sure I did a fair comparison, so I threw the Black mac on the test bench to make sure it pulled close to 32-1/2” H2O like the chrome Mac.  To my surprise, the Black Mac only pulled 26” H2O.  I spent a while swapping the two mufflers back & forth on the bench.  Chrome 32-1/2” H2O, black 26” H2O, over & over.  What’s up with that?

I placed the two mufflers side by side.  It was evident that they are different.  The black one is shorter.