I shoot the helicopter in the beginning to make it fly faster, this saves 26 seconds. I used the weapons glitch to get the rocket launcher. I use this to blow up a speed boat from across the map since it's required to finish the mission. Then I run straight to boss. I use a armory to refill my rocket launcher so I can blow the door to the boss as grenades don't work on the door. I take down the boss and do a grenade boost over a wall to bypass a lot of enemies. From there I run to the end.