I almost bought a 2-1 off e-bay for my CB175, but it doesn't quite fit because it was made for a 350 twin. It was listed for $39.99 by a guy in Montreal; e-bay #: 4644805556 (ended).
He sent me some dimensions:
"Hi Chris,
here are some details on , measurements and some photos,
expipe diameter 1and11/16" at head,
expipe centre to centre 6" at head,
length from inside of top pipe top top of lower pipe 11",
length from inside of down pipe to end of pipe 16",
collector pipe diameter 2",
muffler length 17.5",
muffler end diameter 3",
removeable baffle it is a street legal system,
rear mount on muffler has about 4" of adjustment,
if it was too loud for you remove baffle and wrap with a new piece of
silencer insulation,
it is nice and clean with no rust"
I've bought a couple of things off him, nice guy & all good deals. Good shipping prices, even tossed in some extras here and there. The exhaust was up at least twice and didn't sell, he probably still has it. The dimensions came with some pictures, I can give you his e-mail if the listing is down by now.