Hi, chingus!

After finishing watching Time Between Dog and Wolf I need more gangster bromances or something like father-son relationship? I loved how they trust and take care of each other... Any recommendations? :< I've seen Cruel City and Black & White.

have you watched the movie Gangnam Blues?  Highly recommended for all of the above
I don't watch movies, because they're too short :( But I'll give it a try just to ease my drama slump ;) Thanks!
Friend, Our Legend --- Drama version of classic gangster film 
Friend --- the original movie


Not Exactly what u want, But Close!:
Chuno ---  Great bromance ... not exactly gangster, but outlaws, etc... 
City Hunter --- Interesting father-son dynamics
East of Eden  ---  Gangsters, family dynamics, lost brothers ..... Bromances that rival the romances .... Not typical melodrama due to exceptional writing!
IRIS -- Secret Agents not gangsters .... weak bromance but interesting relationship and friendship dynamics .... similar to Time Between Dog & Wolf


Movies:
A Better Tomorrow --- Gangster bromance and brotherhood
Guns and Talks --- comedy gangster bromance
Parts of Inspiring Generation might fit what you're looking for (also on your PTW!).  I gave up on it halfway through, but the beginning's pretty good, and it has some stuff like that.
Tong: Memories
Bad Guys
Wild Heroes
KO One (comical gangster-ish bromance)
Triange (slight bromance)
Secretly, Greatly
Bar Legend
Tokyo Dogs

this is not at all a gangster drama at all, but its my favorite bromance: Aozora no Tamago
Holyland
Kaitou Tantei Yamaneko - they're not gangsters, they're thiefs, but you get the same vibe and the bromance is really great and the storyline as well
Kids (movie) - one is kind of a rebel (or a thug, I don't remember exactly) and the other is a very innocent man
Maou - one is a police officer and the other a criminal

Also, sorry to say but I did see your list and I must say, you're as big of a mess as I am xD
Thank you, guys! I'll find something for sure! ;)