I don't know, the bike doesn't run yet

but I was pretty happy with the way it looks

Seriously though, I used the dimensions of a stock muffler as a pattern. Mine is slightly longer and a bigger diameter, and so is the new muffler. boom tish.
Also, the core I've used has slightly bigger holes and I'll be using a decent muffler packing. The original mufflers were a one piece item and I made mine to be repackable, so fingers crossed.