Right after the first tutorial on bullet time and diving, run past the door where you shot the first enemies and look for this Gun Part on the ground by the window.
CLUE: CELEBRITY MAGAZINE
This is on the coffee table in the swank room you kill the first enemies in. Activate this before exiting onto the porch.
GOLDEN PT92 PART 2
After the scene where Max slides down the roof and frees the hostage, you will gain control again inside an office area. Run past the circular desk area and look for this Gun Part in the corner to the right. It's in front of thewindows between two columns.
GOLDEN PT92 PART 3
After hitting the green button in the parking garage, stay to the right in the next area. This Gun Part is on the ground in the corner. Get it before heading up the ramp.
CLUE: DROPPED PHOTO
After hitting the green button in the parking garage, this is on the ramp leading up to the next level of the garage.