I know people who have ordered from them before. I'm about a week away from getting an 2.5" stainless exhaust for my CRX from them. Yes, you do need to get resonator, muffler, and downpipe seperately.
Downpipes are rarely included with a catback system, that's why it's a catback.

The hangers and flanges are included. I just have to find a quietish muffler and take the TIG welder to it when it comes in..