So...I'd originally started this thread over in the ///M section by mistake, and figured it might make more sense to start a new thread here in the general e70 section with the proper subject line for future searches. I paid $400 for this on ebay shipped to my door. It took my local muffler guy less than 1/2 hour to hang it and weld it. It's all stainless steel, and the craftsmanship is readily apparent. The factory muffler weighs 39 lbs., and the Megan weighs in at 25 lbs., so you gain performance just from the weight loss, but it does add a few HP too. The fit is great, and the sound is awesome, as you can tell from the driveway revs comparison. I'm going to post a couple of more "before and after" drive by videos when I get a chance.
Here's a photo after I'd taken the Sawzall to the old exhaust: