I was put on to this by a guy at work who has an MG. He showed me the parts catalogue for the MG & I loved the detail it was like looking at the blow-up plans you used to get with Airfix models as a kid.
They also supply MX5 parts and the catalogue is free - but it seems the MX5 catalogue is undergoing some update.
http://www.moss-europe.co.uk/parts-accessories-catalogues/mx-5-parts-catalogue-mx5001.html