Do you still have the stock headers. If so, I also have a pair of stock slip-ons with about 600 miles on them. Send any reasonable offer plus about $30 shipping and they're yours. The slip-ons are from my '08 883.
What kind of slip-ons are on the bike now? You might be able to get some quiet baffles for them. Show us a picture, someone may be able to ID them for you.