The beauty of it is that you can run whatever you want. The header pipes terminate at the same point as the stock header. I opted for 1 3/4 outlet so I could hook it up to the pipes I had, which means I could have hooked it up to any stock pipes (2 or 3) or other pipes that fitted to a stock header, such as Staintune. I believe the header/can combo is 2 1/4 outlet and yes, is a single can, but you can of course fit whatever you want to the header. I'm happy with the smaller outlet. Certainly have gob loads of torque and I don't like to run in high rev range. I reckon 2 1/4 could be a bit breathless unless you have other mods. 2" maybe a good compromise. Just my thoughts though.
Pretty sure Bruce's, by the way, was a one-off and is a bit different to what you'd get.