I'd say be wary of Malaysian coilovers. I know a couple of people that have managed to import them into the UK, and the quality is less than ideal. I'd also suggest being wary of who you import with, if you do choose to go Malaysian, myself and many other forum members on here have been scammed by a seller called "Keicar 4 Life" so I strongly advise avoiding him.
Japan is another option, though. They're usually quite expensive, but the quality is always superb. K Takayama Parts Emporium is a good importer that a few of us use on here. Same goes for boss kits (I've had a quick look for L251 boss kits in Europe, but couldn't find anything).
Looking forward to seeing the progress with your car!
1998 Daihatsu Mira TR-XX Avanzato R4
1991 Autozam Carol Type-G
1994 Nissan S13
1997 BMW E36 316i Saloon
1996 BMW E36 323i Compact (Sold)
1998 Toyota Chaser JZX100 (Sold)
1998 Toyota Soarer JZZ30 (Sold)
2000 Perodua Nippa L201 (Sold)