I would delete it if it was up to me. They put soot in the intake tract, leak, make complicated mess under hood, cost MPG... no good reason for them at all. My 6.4 in my 2011 5.7 truck without EGR pulls much better than an actual 6.4 truck, quite a bit more tq, MPG and throttle response but part of that may also be the 5.7 eagle cam and heads.

08 was the last year of them on 5.7s ( I think maybe there were some hybrid durangos that got them in 09) in trucks and cars, they could bleed off cylinder pressure by adjusting cam timing and reduce NOX emissions that way instead.