Okay, so I just bought a separate intake to put my su's on. I am pretty sure the crossover manifold I have with Strombergs is leaking at the bizarre intake butterfly linkage (though to be honest I did not put a lot of effort into troubleshooting either the carbs or the vacuum leaks beyond new hoses). I also confirmed that I have a vacuum retard unit and the combination is not doing fuel consumption any good.

So my question is about the exhaust side of the combo manifold - will this flow decently enough for HS6's and a D cam with a somewhat straighter pipe and free-flowing muffler? The car has a leaky exhaust and it sounds like a few loose baffles in one of those mufflers anyway (i.e. it sounds like crap). I don't think a header is necessary (nor do I want to pay for one) and I do have two of these combo, butterfly-riddled, leak-ass manifolds. I have heard that the exhaust side is not so bad on the combo manifold but I have also heard that there is a combo manifold without butterflies and maybe the reference was to the non-butterfly combo manifold? Thanks in advance for your advice. Aaron