Mike, I would give Kev a call tomorrow but I see you have done that already.
My bike was the test mule for the Keihans and they are superb and sold a few on the back of people seeing mine. I think they are top quality and at least as good as Akra and Remus where you pay for the name. Mine have doe 100,000 miles now and have been to Alaska 4 times in some of the worst road conditions you will find. I'm not an avid bike cleaner either but the headers come up beautifully when I can be arsed to polish them, which isn't very often.
When mine were fitted, I tried lots of combinations of end cans none of which makes any difference apart from noise.
I've found you need some back pressure for the engine to work properly so keeping your OEM end can is a good idea unless you want to lose a few kgs.
For the best results, Keihan headers, standard (or baffled) end can and either a remap or Power Commander.
My set up is Keihans, an American FTP end can and PC111 dyno'd and fuelled to my riding style. I can't fault it.