The Mac muffler is a reverse cone.  It’s a handsome devil.

As you can see, the Mac is straight thru.

The Cherry Bomb is (what can I say?) a typical Cherry Bomb.  Somewhat crude.  It sports an ample 1.75” diameter hole straight through the center.  It’s a featherweight too.  I’ve had this one for several years.  As I recall, I bought it at O”Reilly for about $25.  It’s a Thrush part number 24210.  BTW, you can also get one of these in stainless steel.

Anticipating that the C-Bomb was gonna wake the dead, I fabricated a baffle tube to snuff out the noise.  The largest practical tube ID is about 1”.  A larger baffle tube will reduce the exterior cross section (area between the baffle OD and the glass-pack ID) to a section smaller than the tube ID.   Sometimes you reach the point of diminishing returns.

Installation requires a 2” x 1.875” adapter.  I was able to find one at O”Reilly auto parts.  Since this was a test, I didn’t get too carried away with the mount.  Just a chunk of aluminum and a couple of stainless-steel clamps.  It worked fine and was easy to do.  If I decide to permanently install the C-Bomb, I will come up with something a little more robust.  Again, with the Mac header, installation is a snap.

The LCGP resonator is polished stainless steel.  Looks to be good quality.  The welds are nice, the finish is too.  It has a mighty big 2.5” hole straight through the center.  I had to install a baffle in this one before I even tried to ride the bike.  I also didn’t bother to test it for restriction without the baffle because the hole through the center is so big that it wouldn’t have pulled any vacuum on my test rig.  I bought it on Amazon for $36 delivered.  LCGP part number 254019.  Website is www.lcgppro.com.

The baffle is just a piece of 1.5” conduit.  It has a plug in the center with 84 holes on the inlet side of the plug and 84 holes on the outlet side.  The holes are .17”.  There is a fitting on each end to seal it to the glass-pack core.  The plug in the center forces the flow to run out of the perforations into the area between the tube OD and the glass-pack ID, then back through the perforations into the tube ID and out the exit.  Acoustic energy is attenuated by restriction, direction change, and absorption.

12/16/20  I also built a LCGP with a 1.75" baffle tube.  Construction is essentially the same with the exception that the baffle tube is larger.  It flowed much better and was significantly faster.  I updated this post to include data on the 1.75" baffle.

I had an extra Mac muffler bracket that I modified to mount the LCGP muffler.  A couple of 5” stainless steel clamps and I was in business.