Don't bother messing with the intake unless you have an aftermarket ECU to handle the changes in metered air flow. You WILL lose fuel economy and low range torque on the 1.6L. Mazda did a great job of overengineering many parts on these engines, the intake tract being one of them. Listen to Brain, he knows his stuff. Suspension and handling is the best bang for the buck on these cars. Work on driving skills and learn just how fast a Miata can be in stock form. Intake, exhaust, and all the typical Honda mods really don't pay off on these cars. Forced Induction is the cheapest way to get a meaningful boost
in power. Unless you just live your life 1/4 mile at a time and really really need to beat that Camry to the next stop light, then you should trade for a Mustang.