The Dynomax "Super Turbo" seems to be the best-flowing of that style, has flow directors at the inside ends & doesn't neck down inside. Good crisp sound, not boomy, very livable with tailpipes. A buddy ran a pair of Imperial mufflers on a SB Chevy PU and it was quiet, about like a stock dual exhaust from the '60s. Ran stronger than stock. I'd go with 2.5" downpipes if the manifold flanges accept them, H or X pipe, 2.5" mufflers, 2.25" tailpipes to the rear corners.
