I bought a set of D-port long branch manifolds new from Ram Air Restorations about a year ago. They had just got a shipment in after waiting over a year. So check stock for sure. They work fine and are nice castings. They have the "cool look" and on a stock or mild build are worth 7-10 peak HP over the stock log iron manifolds. They are expensive and require the oil filter adapter for proper fitment. By the time your all done, it's a minimum $1000.00 deal with all the parts for 7-10 HP. Headers cost about the same but always have to deal with fitment issues, rust, noise, ground clearance, exhaust leaks. Decent set of headers on a stock type build probably an additional 5-7 HP peak HP over the long branch manifolds. Decisions, decisions. As HP creeps above 400, headers become more important for best HP. My recent build took a 28 HP hit on the dyno between long branch manifolds and a set of lousy "dyno headers" we had laying around. But my engine was large, 467 CU IN, and just under 500 HP with the headers.
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