Like C/S says, 4V clevelands definitely prefer split pattern cams, biased towards the exhaust side ofcourse. They also like lift more than duration.
As far as manifolds go (and cams), it depends on what you want or expect from it. Nothing wrong with the Torker, the Performer (don't make an RPM for the 4V) isn't a great deal better than the stock dual plain though much lighter ofcourse and the Air-gap will give you abit more mid range than both of them but probably still give away some top end to the Torker.
If you are going to re-cam, I would stick with what you have and see how you go... a better grind will also give you more mid range punch than you have now anyway. If you want more bottom/mid-range after that, pay the dollars and put the Air-gap on. Torkers really like a spacer as well....

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IF YOUR USING OTHER PEOPLES IDEAS YOU ARE ALWAYS GOING TO RUN 2nd.......