And just to throw it out there since I am on a fabbing frenzy kind of mood right now I'm going to make an intake horn just like Hellmann's except it won't be aluminum (no way of welding it right now). I don't ever use the grid heaters anyway...

http://hellmannperformance.com/intakemanifold2.jpg

Even if this kind of turns out to not be worth ALL the effort it WILL be pretty unique IMO lol, and all done by me so...

 

There are advantages to the multi piece exhaust manifold even if Hellman can make insane power on his. Thats why the bigger trucks come with multi piece manifolds- to prevent cracking by allowing for expansion/ contraction.

 

How do you get those pesky injector line out of the way? Must been a custom fab for the injector lines my guess. For 600rwhp your don't need anything too exotic, IMO. I remember someone fabricated up a custom intake that had an air tube for each cylinder. The fella told me that it helped egt's abit and improved spool-up. I just went from a stock intake runner/stock intercooler to an ATS intake and spearco intercooler. If I didn't pull my own wrenches I would be hard pressed to see an real improvement in my sop meter. That exhaust manifold is one beefy unit. Take pictures and update us, a few of us enjoy fabbing up neat/cool stuff like that. Good luck.