Not from NYC, but yeah I've heard about them. They were mostly muscle for the Cantonese-speaking Tong organizations based in NYC. Most of their members were immigrants from Guangdong and Hong Kong.

Nowadays immigration from that part of Southern China seems to have cooled down. There's probably still organized crime in NYC connected to the Cantonese groups, but more under the radar.

Fujianese groups make more noise nowadays when it comes to Chinese OC in NYC (largely because most of the new Chinese immigrants coming into NYC seem to be from Fujian).