the XF never really goes back to 2, its just one pipe into one muffler, and the dual tips are nothing more than aesthetic.

even if the car had dual exhaust, it couldn't take advantage of them without some real headers; the factory exhaust manifolds hardly compare.

and remember, it was based completely on the SLK, which started life as an s/c'd 230 inline 4; that's where the single pipe design came into play, so that when it was bumped up to the v6, they already knew the exhaust's "design." moreso, back when the car (and the 3.2L) was designed, it wasn't even DC -- all Chrysler did was design the pretty silver engine cover.