You think there would be a market just to make the manifolds to mount the headers?
We'll build a twin turbo car at some point, but no one has stepped up for a build like that yet that wanted to spend the money to do it.
I think if you could get castings beefy enough that would fit well, I'm sure you would have takers for new Hemi and RB/B designs. I agree on the turbo headers. I have friends with seriouly boosted mustnags (Fox body, not the ones Scotts into...lol) and he popped his at a rental due to heat cracks at the welds. He runs serious boost, single turbo, and can run 8s on radials. Street car...lol. I would love to see a basic cast turbo manifold for them. In a typical log style with tha flange above the #3 plug on the driver's side, and #6 on the pass side, that would fit almost any chassis.
The 2.2/2.5s make 2hp/ci pretty easy with the factory log style...