Probably to ensure quality connections, the adapter has a few inches of male pipe which sleeves into the stock connecting pipes. The few inches of that sleeve prevent you from installing the x-pipe section without also dropping the rear/muffler section. This is probably not usually a problem since most people are buying the full exhaust and will install the rear mufflers last instead of trying to squeeze this midsection between an immobile front and rear section. So what started as a 45 minute bolt-on plan turned out to be about 2 hours. Still, not bad all things considered.
Reason for that is, to make it reversible if you change your mind and want to go for the Akra Slip On later on also