The PlayStation 3 and Vita versions of this mission are related to a trophy named "What's That Smell?", completing this mission will reward you with a bronze trophy.
An escort mission and an especially tough one at that too. The last visit in the Haven sewers has you protecting Jinx, Mog and Grim from the new hosehead Metal Heads that infested this place in large numbers. Hoseheads will climb down walls to ambush you and have a powerful long range laser beam attack, their melee capabilities are mediocre however as long as you watch your back.
What you want to do is rush ahead and take out as many hoseheads that appear before they can deal any damage on the three guys. They're pretty useless and might fire a lone shot with their pistol when one gets close, but don't rely on them otherwise. It's also recommended to try and conserve ammunition due to the final fight in this mission. When you get to the first room you'll be attacked by several hoseheads who climb down the wall, you should be able to kill all of them with a melee attack and roll jumps to close the distance.
Stay clear of the explosives (just stand with the other guys as those positions are safe. Rush ahead of them again and quickly use the Blaster to get rid of the two up ahead, then turn around and take care of the two who were going to attack you from behind. Head forward again and take the elevator down and in the passage with the water you'll want to do the same as last time. Get rid of the one sin front quickly, then rush back to get the ones who came from behind.
When you approach the next turn you'll be attacked by another three hoseheads positioned at the end of this corridor. They'll have the floor pretty well covered with laser beams (the beams go from left to right and back again at a relatively slow pace). Carefully jump through the gaps to get close enough to shoot the hoseheads (you might not have enough time to aim the Blaster, so get close enough to shoot all of them with the Scatter Gun). The next turn you meet the same situation but this time you can use the metal grating in front of you as a shortcut (using the JET-Board). If you do that you can safely flank them from behind.
After the cutscene you'll be ambushed by an immense amount of hoseheads coming from above. The majority of them drop at the bit with water though several will fall down dangerously close to the guys you need to protect. Avoid straying too far from them before they're cornered behind you. You'll want to use all your ammo available, use the Scatter Gun to knock them back, use the Blaster's combo moves to take down several in one go and the Vulcan Fury to mow even more of them down. Use Dark Jak's Dark Bomb or Dark Blast as a last resort if possible.