I always thought it was too little ganginfluence in Vice City so i simply added gangs in some locations i thought needed it.
There are:
Streetwannabeés in The Docks and in the ghettos.
Diaz gang added in Ocean Beach.
Cubans added around Malibu Club at night.
Bikers added around Pole Position Club at night.
Securityguards around Ocean Beach.
Vercetti Gangsters added to Malibu and Ocean Beach.
It will make very funny gangwars around these locations.