There is not much room in the tunnels thatare either side of the fuel tank, I doubt you'd get any high power 12"
driver to fit - even if you placed it so it was sticking out vertically in
some sort of double chamber reflex enclosure. I've done some measuring with
a set of 10''s and it would involve LOTS of work, including cutting lots of
metal. I doubt then you'd be able to make it solid enough to prevent
vibrations etc. Some 8's can be mounted flat, but only just, and with not
much support, and only really in a free air configuration.
If you really want to fibreglass a 12' in there, I'd go with the 'remove the
spare' and build a very solid sealed box in the contours of the tyre well
and surrounding area, but making sure it can be removed at any time. Find a
driver designed for a small box size (a number of manufacturers make them
now) and feed LOTS of power into it. Use a basic 12dB/octave active
crossover, but crossed low - say 40-60Hz
I wouldn't recomment 6x9 - you can get 100's of brands of much better
quality 6"or 6.5" component sets cheaper.
I think the better option if you are going to the trouble of 'custom roll
bar pods' would be to build these around 6"-8" subwoofers and forget the
boot. Your amplifier(s) will no doubt have to go in the boot anyway, which
may take up enough room. Save your 6" (or 6/9) components for the front...
where it really matters.
Obviously make sure you can still get your roof up & down easily with these
roll bar pods! and remember, what thieves can see, they will nick - esp if
you only have a cloth roof to stop them...
have you checked out http://www.canze.org.nz ? Go and have a look at some
competition cars and get some ideas from the pros.
Naysayer Disclaimer: no you can't really get amazing quality audio in an
MX5, but it is fun trying. I believe I got close with my last car - I built
a crappy web page a long time ago which is about 10% complete at
http://www.fox.co.nz/mx6/
