If not already done here are the Necessities before you start with go fast mods on a 6.0
ARP head studs
OEM Gaskets
Heads pressure checked
Heads machined flat if need be
Egr delete, or ppl have luck with the Bulletproof EGR Cooler (depends on your areas smig restrictions)
New Oil cooler
Coolant filteration system
Have the intake manifold cleaned out
Have turbo cleaned out.
Update fuel pressure regulator spring (Blue Spring)
Install a fuel pressure gauge (anything below 50 psi WOT is a problem IMO)
Now you have a perfectly reliable 6.0 provided all work was done properly.
Then its time for go fast toys but the trans tends to not like anything north of 600 HP.
You should be able to get the necessities done at a shop for 4-$5,000
Ive recently been through all this so any questions feel free to PM, there are quite a few indicators that let you know if this work needs to be done pronto or if you can put some miles on her first.