I pulled my Db killers out, the pipes were installed on the bike at the time. I pulled the rubber bungs and got at the screws and subsequently dropped one down inside the can. It's not the best design. I was able to drag it back up and out the hole, along with the washer using a strong neo-magnet.
A question for those who pulled theirs out too. Did you replace the rubber bungs into the outside of the cans? I did, and I hope exhaust gases don't fry them!