You're going to need to add some tailpipe to this system in order for it to exit aft of the rear axle. Just out of curiosity, why didn't you just order the system that includes the full tailpipe? It already has the resonator and it seems it would be easier to just cut off a foot or two from the full system rather than add to the turndown system.
I've had previous systems with a full tailpipe exit fall off and get crushed offroading. I currently run a modified magnaflow that dumps over the axle and it's great for eliminating drone. Magnaflow just isn't ballsy enough.