I missed this thread earlier. I've got the same one as Darren in 14". Put about 3k miles on it attached to my 250R then modified it to fit my 300R and it's done about 13k miles on that bike.
Glad you are happy with your purchase, like you said they are excellent value for money compared to the top line slip ones and have a nice note particularly on deacceleration. I've always run it with the baffle in.
I have found that it's got noisier with age tho and these days is probably verging on being a touch loud for my liking. It probably just needs a repack but I won't bother as I plan on selling the bike this summer (your winter).
With that many miles on it and considering it's initial cost, I probably wouldn't bother with a repack either.
I wrote to Delkevic, letting them know how pleased I was with the new muffler and got a nice response back.
Great, responsive company that makes an outstanding product.
I'm surprised more people don't consider the Delkevic as an option instead of mufflers costing twice as much.
The tone of this muffler is exactly what I was looking for and a couple of friends with Suzuki Gixxers are mightily impressed with how my CBR250R sounds now.