I have these sitting around my garage. I'm not sure if I'll ever actually need them again because I plan on keeping my car for a long time, and I love my Berk system..
I was originally planning on keeping them "just in case" but garage space is at a premium and so is money, so if I can get a decent price on either my stock axleback or my stock midpipes I'd probably be willing to part with them.
I'll just leave this here and if anyone needs these parts, don't be afraid to PM or leave a post. I'm not 100% set on selling these, but if anyone needs these for a lease return or something like that and I can get a fairly decent price, then I'd be glad to unclutter my house. Please take into account shipping or local pickup in NJ.
For reference here are the part numbers and retail prices:
Rear muffler with exhaust flap. PN: 18307559995 $858.81 (axleback)
Rmfd catalyst with muffler. PN: 18307559994 $2,170.94 (midpipes)
Axleback has about 8,000-10,000 miles. Midpipes have about 15,000 miles.
Thanks for looking