Mount so that you can replace the sun visor in your NA Miata with a tweeter.  Designed for the SB Acoustics SB14ST-C000-4, this is probably the only tweeter that will work.  If you plan on using this I'd highly recommend a fully active setup.  The distance between the door speakers and tweeter is huge, so unless you use a DSP to time align everything it probably won't sound great.