I spoke with one of the main head honchos over at XV.
I'm working with him on a quote for a wire harness for 5.7L Chrysler alternator using the bosch connector.
Anyway...
I brought up later on in the conversation about the re inforcement side bars. His thoughts were that if you are going to change the K member to one of the newer aftermarket styles that are box framed, then you will definitely need these. If you are running the XV motorsport sub frame connectors, then you should also get the front lower radiator support mount re inforcement bracing. They don't hurt to have added also but the main torsional body shifting and movement generates from below. It'll also depend on what type of driving you do. Drag vs. Road race.
