I always thought the use of the sax in the robbery scene from Boyz N Da Hood was super effective. Starting off soft and more composed, but becoming louder and more unsettling as the robber moves inside of the house and Trey gets up to piss, while Furious loads his pistol
It's almost as if the sax's pitch and the bass underneath represented my man's heart rate through the scene, steadily rising.
When Furious aims his gun and that sax starts screaming
The entire score for the film is really beautiful, and really ties brilliantly into each scene. It's one of the things that elevates Boyz beyond similar hood films.