I'm not exactly sure why, but the video link that showed the muffler and its rattling debris (after only 2 weekends and 200 track miles) never made its way into my previous post. Let's see if it works this time...
https://www.youtube.com/watch?v=7gepRKnHosk
FWIW, I'm now building my own single-side exhaust on the passenger side, with an over-bellhousing crossover from the driver side. I can post pics if anybody still cares.
Mark