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.
Click here to go to the Extrude Hone
Questions?  Comments?  Send email to: 
reted@fc3spro.com
03/13/2004