This is our top-of-the-line medium profile street performance manifold. It is similar to our 52000/52001 Cyclone, although slightly taller, but with several important modifications. First, it has a square bore carb flange instead of a spread bore. The square bore flange permits direct bolt-on of all popular Holley, Edelbrock, Carter, and Demon carburetors. This manifold is also the only SB Chevy manifold available that features a built-in rear water crossover passage. This typically will provide for better overall water flow and cooler engine operating temperatures. It also features nitrous bosses, and rear water ports. This manifold will typically produce more power than any similar competitive manifold due to larger ports and runners.