I'm assuming you are looking for a shop that sells used skyline parts, be it stock or performance hence u r asking for biggest chopshop in Klang Valley.
There's one i know of, quite big. Infact the biggest in town. It specializes in used skyline parts as the owner has one. He buys new parts and takes out his own. He replaces the parts so often that it has grown bigger than mun lee and sun eng hup put together. The shop's spread out from Paramount, to sec6 pj to bangsar... that's how big it is. It's rumoured to be spreading to titiwangsa and kepong too...
U can contact the owner...
pm him
possible parts:
Skyline,
Ferrari
Porsche
Jaguar
Benz
darkchild
WAHHHAHAHAHAHAHAHA
*CABUT*