I have heard that they will quiet down an exhaust. Is there really any performance advantage? On my little SB I am running headers through 3" mandrel bent and 40 series flowmasters with no H or X pipe.
id at least go wit a crossover(h-pipe)it will help ballance the left and right banks,and scavenge better.in one of my books it shows dyno testing with both.the x pipe was worth 11 hp over the h.ive never run an x pipe,dont know how it affects sound.