id like to recomend FST automotive, based in sthingyhorpe, north lincs
they specialise in modified cars of any make/model but will take on normal garage services as well
they have a fullt stocked shop and can mailorder items out as well.
www.fstautomotive.co.ukthey keep quite a few golf parts in stock including coilovers,air filters,strut braces,exhausts
and they can even custom build stainless exhausts on site