Generally speaking, at the factories, car manufacturers fit one piece exhausts, or at least the mid/rear section is one piece, they can do this easily as the exhaust will get fitted before the rear axle/beam is fitted. That is one of the reasons why most car manufacturers sell two piece mid/rear sections - ie as there will be an axle/beam in the way! VAG tend to supply "plain" ended exhaust sections and joining them is achieved using joining pieces - which works very well. Also, in a standard car with standard exhaust, you cut the exhaust at the correct point if only replacing "half" of the mid/rear section, and buy a joining piece to fit new section in.