Check it out...
http://www.300zxclub.com/showthread.php?t=59236

Looks like a more durable and more affordable setup than the iconel manifolds that Specialty Z sells. It'll be interesting to see the dyno results.

 

i was also reading where scottsi was going to try to make some cheap ones as well

except i really dont why they are so expensive

 

I wonder how they flow?
Carlos Ramirez has a point. Good way to compare them is to have them bench tested for flow.
Also i'm wondering how turbulent it is or isn't on the inside of the manifold. Just like the exhaust after the turbo, smoother with less bends is better, those manifolds go 90degrees directly backwards.