Heads...They have come a long way. And you can either pay for someone name that says they work, or you can pay for just ones that work. If you pay that much you better have a 2000+hp rocket ship.
Example of new stuff.. A set of trick flow heads can be had for $2k that flow 275 and a set of Stock GM L92 heads with the same good parts can be had for $1k that flow 325 untouched. A couple years ago they were not available.
Research and knowledge replaces high priced parts. I just been reading a lot of peoples builds and am blown away at some of them. They spend a ton extra because they dont bother to research anything (mostly on other sites).
Theres a place that makes turbo "kits" and what they include is factory truck manifolds (lsx style) and a basic Y-pipe from the manifolds to the turbo. And a down pipe from the turbo down. This is called the "hot side". They want like $1500. for this hot side and people are like...WOW thats awesome. This is something your local exhaust shop can do for $200. Heres a few pics. And....people have made 1500hp with kits like this. Considerably less than $40k. I think it looks like crap though. This is not my stuff....just pics i found.
For $3700 you get (i think its a rip off)
TC76 Turbo Setup
-6.0L Manifolds
-Mild Steel 2.5” Charge Pipes with a T4 Flange and Integrated Waste Gate mount and narrow band O2 bungs
-Mild Steel 3” Down Pipe with a Wide band O2 bung
-Turbonetics TC76mm Turbo
-TurboSmart 38mm Waste Gate
-TurboSmart Blow Off Valve
-Front Mount Intercooler 31”x12”x4”
-Stainless steel 3” Intercooler Pipes with Integrated BOV mount
-4 Ply Silicone Couplings
-T-Bolt Clamps