Exhaust for a slant

I wouldnt do dual exhaust unless you so everything else. like oversized valves, ported head, bored cylinders, a good two or 4 bbl carb/ aluminum intake, and of course a good cam. Unless you do all that it would be pointless to go dual exhaust or even large diameter single. Stock these engines just dont flow air very well but if you open it up then..:prayer:. I have all this done to my slant six and I drive it on the street. It hauls *** and is very loud if I step on it. as for loosing top end HP with dual exhaust. I really couldnt tell you. I think the difference is in how you build the engine.
:thumbrig: