Here is a break down of every part # needed to make the switch to long tubes + catted high flow mids. These part numbers will work for 5.7L and 6.4 Hemi cars (challenger/charger/300)

BBK Headers: 1648
BBK HIgh Flow Cats: 16481
Header Gaskets: OEM 5038099AA + 5038098AA
Hardware: KIT007 + KIT253-17
Extension Harness: 11181 (24" rear) + 1118 (12" fronts)
OPTIONAL AEM Wideband X Series 30-0300