Dual exhaust for my 273, 2, 2 1/4 or 2.5

2 1/4 gets my vote. I would fit in a x pipe too. To do it correctly you will need to modify the transmission crossmember because it is only designed for a single system. I put the original styled single system on my 66 made by Accurate LTD. It fits well, works well and sounds good. A little spendy though. tmm http://www.accurateltd.com/1965-67-273-Hi-po-System-for-Barracuda-Dart_c_69.html