I don't believe in weighting down a lightweight sports with tons of sound deadening, x-overs, amps etc. It's a bit of a fool's errand, unless you enjoy that sort of thing.
However, mfr.s usually install the cheapest, nastiest speakers and anything with a better cone & decent magnet will improve response - particularly the mid-bases in the 86's doors.
They're not bad, but many Japanese cars seem to suffer from a thumping bass, but then a hollow until the mid-range. The one on my S2000 made me feel quite ill, until I dropped in some fairly basic Kenwoods.That's what presently I have in mind for UZU and why I'd like to know the full spec. It seems to be different from the USDM versions.