My rear valance does not have the cut-outs for tips so I'm gonna use the turn-down approach. Some have said to turn the turn-downs
very- slightly inward towards each other to help minimize drone & noise....
.....don't know if that makes sense. I'm also using a fuel-cell, so NO gas tank to worry about, so I could even run the tailpipes closer to the centerline of the car. I've seen this on some cars (not challengers, though!) where the pipes looked pretty slick being centered and only about 18" apart. Don't know how that would look on a challenger/cuda though. I'll have to get it up in the air and experiment with location and see how it looks.