Anyone recommend a good supplier - I need an uprated clutch and wouldn't mind a super light flywheel too if the price is right

http://www.helix-autosport.com/products/performance-clutches/mazda/

I used these 2 places when I had a mk1:

http://www.autolinkmx5.com/clutch--transmission-parts-mx-5-mk1-414-c.asp

http://www.mx5heaven.co.uk/acatalog/MX5_Transmission___Clutch_222.html

Couldn't recommend uprated kit though.

If you have a 1.8L then you can use the MX6/Probe V6 clutch plate and cover which fits the 1.8 flywheel.
Lightweight flywheels can be had from Flyin Miata in the states - I've always found them nice people to deal with