Due to the increasing popularity of large displacement big block Chevy engines, the engineering team at World Products has developed these new Merlin-X intake manifold especially for 509 and greater cubic inch BBC applications. What's more, these manifolds have been designed expressly for use with large 4500-series Dominator-style carburetors. Extensive flow bench and dynamometer testing has shown them to provide excellent performance throughout a wide rpm range. While the Merlin-X's are single plane manifolds, their plenum dividers and other design features give them the kind of throttle response normally attributed to dual-plane intakes. In many larger c.i.d. applications, they've proven to out-perform top of the line cast manifolds from other manufacturers.