There isn't too much that can done with the intake manifold, except for 1) match porting and/or 2) Extrude Honing.  Match porting just grinds the ports down so air flow is maximized.  This is easily done by tracing and outline using the stock OEM Mazda gaskets and then grinding the excess out with some type of grinding tool.  Extrude honing uses an abrasive media that is pushed through the intake manifold to optimize flow throughout the entire intake manifold.
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