shamefully i run a set of 15" voodoos. they're ok but they say max power way more than club gti (soon to be replaced with rh classics - black centres, polished lip)-(not to be confused with rh classic-lines!).
there are loads of rims people seem to go for but it does depend on the style of your car. are you pre 90 spec? small bumpers etc? because in that case i'd be tempted by some 14x8 steffans or rh's. there are always ronal turbos although i'd be tempted to search for the early ones! the new rims that dubmeister have in stock are CXN th-mono and they look really nice on a pre 90 car, good money too! post 90 spec, big bumpers etc. the ultimate is bbs splits but they come at a cost! otherwise, try azev, brock, kerscher, ats, schmidt (th-line, ooooo baby

), borbet. it's an ebayfest! good luck