I've got unsilenced h-dev ones with a scorpion exhaust (and very soon Stillen Y pipe), Jez said there wasn't really much difference between the two.
Just ensure after fitting them that you check the connections between the exhaust parts, tightened up fully, as well as checking for any leaks elsewhere with the engine on. My one has a slight leak between the end of the y-pipe and the start of the scorpion exhaust, so it makes an annoying noise at the mo