Ill start with the ones i found, post more if you have them:
http://www.draganddrift.com/
http://www.torque-imports.co.uk/index.php
http://www.bonsaicars.com/
http://www.mr2-direct-imports.co.uk/
Some of them advertise on autotrader so its worth looking on there too.
Japanese Performance - Back of that magazine is full of adverts :)
Ill have to grab me a copy then :p
Id try the large number of importers in Dublin before Id try the imoprters over the water so to speak - there seem to be better deals to be had, and a lot of them have been in business since the early 70s.
Isnt it better to make a list of known trusted importers?
Unless you know the importer is good I would have thought a list with some dellboy companys thrown in theres not going to do anybody good.
http://www.neweraimports.com did my car, would heartily recommend.