My 100% dead honest opinion is that you're doing a lot of work and money for mods that are going to get you minimal to no gains where you want/need them (low RPM) but some decent gains if you were taking your XK down the track. It's going to sound badass for sure.... but man, for an offroad truck you could put that money to much more applicable mods (CV axles, winch, etc).

With that off my chest....

With that said; The only part of your plan I really don't think is worthwhile is the magnaflow cats..... unless you're planning forced induction in the near future (which would be sweet... but then you'll really need upgraded axles! lol)