High flow exhaust Manifolds?

Does anybody make high flow exhaust manifolds for a bodies? I have headers, but am getting tired of the clearance issues I am having with them. I've smacked high spots in the road twice now and one pipe is almost collapsed. I'd love to go back to manifolds, but not the crappy flow!
Any help is appreciated! Thanks!

Installing Exhaust Headers Into 300hp Crate Engine - Mopar Muscle Magazine

Here's a header manifold shoot out, there's not much deference in HP between manifolds normal 360 are the best deal.