Then peel the tape away.  Note the four holes that I previously drilled & tapped for the 10-32 screws that hold the new end cap in place.  There’s not a lot of thread engagement, but as long as you don’t get carried away with the screwdriver it should be sufficient to hold things together.  If you strip it, then sheet metal screws will be in order.

It doesn’t look too bad.  I like the megaphone style and you can’t even tell it’s been cut open.

How does it work?  Not as well as I would like.  It definitely is quieter, but not enough for my taste.  It reduced the sound level about 3 dB.  Here’s the new numbers for idle/3000 rpm/4000 rpm.

70/80/83 dB

The sound quality is much nicer than the chrome Mac, and a bit nicer sound quality than the as-delivered Black Mac.  Almost no high-frequency rat-tat-tat, just a low frequency thud-thud-thud.  Lot’s of cackle-crackle on deceleration, but no Ka-Booms.  At idle, it is acceptably quiet.  At small throttle openings, it’s a bit loud but acceptable.  You can easily cruise around the neighborhood without making any enemies.  But open the throttle and all bets are off.  It’s very loud when you start getting on the throttle.  You will most certainly attract attention.  I could live with it, but prefer not to.  I want to be able to wick it up without alerting the local constable.

As far as performance goes, it’s killer-good.  It pulls 3rd gear 4K to 7K in 6.72 seconds.  In comparison, the Dyna muffler does it in 7.83 seconds and the chrome Mac does it in 7.21.  This is a fast muffler.  Too bad it’s so loud.

I hope you find this report interesting and useful.  It’s not too hard to install packing material in one of these mufflers, and the packing brings the noise level down a notch or two.  The same mods will work on the chrome Mac.  

As always, I welcome your questions and comments.

Stay positive, test negative,

Mike

Very cool step by step breakdown, DragBikeMike! I've really appreciated everything you do to share your knowledge!