Just because the truck was equipped with a Predator tuner doesn't mean the head gaskets went. I drove my last 2004 6.0 from 185,000 to 225,000 before selling it. The whole time I ran an SCT X3 from Innovative on the Xtreme Race file daily. I even hit the drag strip a couple times and the stock head bolts and gaskets held up just fine. Eric at Innovative is one of the top guys to tune a 6.0l and thats what I run in my new truck (2006 6.0l). $600 is a rip off! I purchased my X3 brand new from Innovative for $508 with 3 CUSTOM tunes, they are $429 with the strategy canned tunes. A custom tuned SCT is the only thing I've ever heard recommended for a 6.0. If I was you I'd look into doing exhaust, gauges, ARP head studs, EGR delete, custom tuned SCT. The stock Donaldson air filter is perfect for stock to mild trucks. I had a 5" straight pipe exhaust on my 04 and absolutely loved the deep throaty sound and whistle I got compared to a 4" kit, but its all in what you perfer. Hope this info helps!