Prepare to Drop
-When the level starts as you're sitting in the drop pod, mash the B button. Then hold the board button so that you exit the drop pod the second the drop pod door blows off. You will fall down to the streets, go immediately to the right. While falling, mash the crouch button, but don't mash for so long, because if you're mashing while you hit the ground you will lose a lot of health.
-Throw 2 grenades at the brutes the second you see the first brute start walking away. Pistol remaining grunts. If you're on OG, the enemies won't move immediately and it makes killing them with the two grenades much more consistently. On MCC, it's really hard.
-Turn around and pistol/nade/smg the grunts. If they drop plasma grenades, use them or assassination to deal with the two brutes. They can do a lot of different dumb things here, like drop bubble shields or simply run away. It takes good luck to get a really good/really fast clear.
-Once you've killed everything, go to the right of the 2nd fight area and look at the phone booth that is the farthest down the line and hold the board button. Keep progressing past the phone booths and go to the closest door, and hold the board button to enter it. If you lost a lot of health, you can get a health pack by performing this jump to get up to the health pack and not have to worry about not being able to open the door immediately. (Don't worry about the title of this video; this jump can be used for every difficulty regardless of IL or Full Game. I advice learning and performing this jump, just in case.)
-Progress through the buildings and past the grunt courtyard until you've completed the level. Use slide jumps where you can.