Heres the map of the locations: http://www.primagames.com/games/sleeping-dogs/primaguides/319/gameplay/14231
It's not very well detailed at all, but all the other map locations list only 14 spots where this lists 16 spots. I can verify there are 16, i've bought all of the house upgrades from all 16 locations, it just takes a little bit of wandering in the area where the number is to find a random person with a speech bubble next to their head. Just thought I should post this.
Out of curiosity, is there any real reason to get these upgrades? Are they anything other than cosmetic?
Some do stuff. For instance you can get a stereo and sound system and play music in Wei's first apartment. --- I named him Waggleton P. Tallylicker. I never got the chance to tell him. He will be remembered. ~ Grayson Hunt