I had a set of side pipes built for my BDR...looking for street quiet and a different look than stainless steel stock pipes. So here's what I did.
I had a car chemistry set of disks put into the collector along with their stainless steel muffler packing, then a chambered muffler with a little more ss packing, and then a baffle extender into the elbow (so it doesn't trumpet with the expansion at the elbow). They were made by Tubular Auto in Rockland, MA---here's their website.
Tubular Automotive
The ss packing is really helpful since it keeps the pipes from ringing when you hit the accelerator from the exhaust packets hitting the disks. The ss packing diffuses the exhaust blasts from each cylindar, reducing the percussion. I then had them ceramic coated and made flat black...nice.
It sounds great...talking on the highway is easy (as any convertible), and it's not quite so tame sounding as undercar exhaust.
The guys at Tubular modified the primaries as well to create a tighter fit. They're fastened with bolts through two tabs. I'll post a sound file when I figure out how to make one tomorrow, but here are some pics. A picture of the primaries as modified but before re-ceramic coated. A picture of the end of the pipes with the fastening tab. Then on the car.
