Take cover behind the counter as soon as you gain control of Lynch. Note that you can earn the Sichuan Specialist Xbox 360 achievement or PlayStation 3 trophy by escaping the restaurant without once being downed by enemy gunfire. This task is very much doable, but will require patience and precision. The weapon that would serve you best in this task is the TOQ shotgun used by police officers. With any luck, you picked up this weapon at the end of the previous chapter and are starting this one off with it in hand. A revolver would make a good companion weapon.
To earn the Sichuan Specialist achievement/trophy you must escape the restaurant without being downed in one go. In other words, you wouldn't be able to unlock the achievement by pausing the game and reloading your last checkpoint after being downed by gunfire.
The seating area is packed with officers armed with assault rifles. Making it out of the restaurant alive is just about whittling down their numbers until you're able to push out. It's very important to make good use of cover here, as these enemies' assault rifles can put you down if you leave yourself in their sights for even a moment.
Escape the restaurant without being downed to unlock the Sichuan Specialist achievement/trophy.
The TOQ shotgun boasts considerable range and is well-suited for scoring headshots on enemies popping out from cover to fire. When an enemy moves out from cover, quickly take aim at his head and fire. Use your revolver or pistol to take out the officers at the back of the seating area. Be wary if you decide to switch cover, as the walls with large, circular windows in the middle of them are destructible and won't protect you.
When the initial seating area is clear, make your way to the back of the area with your shotgun ready. If one of your weapons is completely out of ammo, trade it for one of the assault rifles left by your fallen enemies before pushing forward.
Watch out for an officer when you turn toward the next area. Put him down with your shotgun before moving up and taking cover behind the fridge on the wall to your right. There's a fire extinguisher right next to this fridge; pick up the extinguisher, throw it through the circular window just beyond the fridge and then shoot it to hopefully take out a couple of officers covering there.
Once you've dealt with the enemies nearest to you, hang back and start picking off the officers at the other end of the restaurant. If you have a pistol with you, use it to deliver headshots. Crouch and sit still to improve your accuracy.
Fight your way out of the restaurant.
Slowly push forward when the way appears to be clear. The game will auto-save and Kane and Lynch will exchange a couple of lines of dialogue when you kill the final enemy. Before leaving the restaurant, press down on the D-pad and search the area for shotgun ammo. If your secondary weapon is low on ammo, trade it for one of the assault rifles used by the police.
Kick down the door at the back of the restaurant when you're ready to move on. A police officer will kick down the door at the other end of the corridor and open fire, so be ready with your shotgun pointed. Pass by the bound workers and lift the door at the other end of the room. You'll unlock the Sichuan Specialist achievement/trophy at this point if you meet the requirements.
Outside, sprint to the other end of the alley, head up the stairs there and follow the corridor back outside. Keep an eye on your left for some stairs as you move forward. Proceed up the stairs when you reach them and pick up the fuel can at the top. With the fuel can in hand, move through the doorway and take cover behind the sign on the right. Once you're in position, toss the fuel can just over the wooden fence attached to the shed and then shoot the can to set it off.
Use your shotgun to clean up the remaining officers below and then focus your attention on the platform off to the right of the shed. Two officers will have moved onto this platform to take cover behind the signs there. You can headshot these guys with a shotgun from your position, so wait until they pop up, then quickly take aim at their heads and fire.
Entering the shed
When the area below is clear, drop down to street level and enter the shed at the far end. Move through the shed and lift the door you come to. There's no need to kill the cowering officer here.
Sprint to the other end of the alley beyond the door and start down the street. A police cruiser will appear shortly after a group of civilians flees from you, so take cover behind the van on the left side of the street and use your shotgun to take down the two officers that step out of the car.
Continue down the street when the way is clear. You'll soon come to a bus. Take cover behind this bus, as a couple more officers will soon appear further up. When you've dealt with these initial two officers, move up and take cover behind the taxi in front of the bus. There's a large police barricade in the kitchen across from the DVD store. There are several propane tanks in this kitchen. You just need to find a way to get a clear shot on one of these propane tanks to dispatch the officers blocking your path.
While covering behind the taxi, look for a ramp next to the pickup truck on the right side of the road. Sprint over to the pickup and take cover behind it. When your health is full, head up the ramp and immediately take cover behind the railing on the scaffolding. From here, you have a pretty good view of the police barricade as well as the propane tanks in the kitchen behind them. Target one of the yellow propane tanks to cause a large explosion, killing the officers at the barricade.
Clearing the police barricade
When the smoke clears, take out any survivors before returning to street level. When the way is clear, move through the blown-out kitchen and climb the wall you come to.
Sprint to the end of the alley on the other side of the wall and proceed up the steps you come to. Drop down from the roof, sprint to the other end of the empty yard and pass through the large piece of piping at the other end.
Another batch of officers will appear when you enter the construction site. Immediately sprint and take cover behind the metal scoop up ahead. There's an acetylene tank on the right side of the scoop. Pick up the can and wait for more enemies to gather by the overturned pillar on the left before throwing the can and shooting it to hopefully take out the majority of them.
After using the acetylene tank, look for some large gas tanks on a dolly along the wall on the right side of the building. Shoot these tanks to set them off, killing any enemies covering behind the pillars on that side of the building.
Pick off as many more officers as you can from behind the metal scoop before moving up and taking cover behind the overturned pillar on the left. Move to one of the pillars further up when the way is clear. Another batch of enemies will appear as you push toward the stairs at the other end of the building. Spray the officers with your shotgun as they come down the stairs. Be careful, as there's a sniper standing at the top of the stairs. To take him down, move up to the overturned pillar at the bottom of the stairs once you've dealt with the other enemies and headshot him with your shotgun when he pops out of cover to fire.
Target the gas tanks on the right side of the construction site to take out the enemies covering there.
With the sniper down, proceed up the stairs and press down on the D-pad to locate the rifle. Hold on to your shotgun and trade your other weapon for the rifle before heading down the ramp to reach the next area.
Two snipers will come into view as you pass the stairs. Both snipers have a distance marker pointing to them, so they're easy to keep tabs on. Crouch to avoid being spotted and move toward the sniper on the right. When you reach the shed, use your rifle to pick off the sniper with a headshot.
Once the first sniper is down, immediately switch to your shotgun, back up and blast the officers by the stairs further up. Use your rifle to headshot the second sniper across the yard when the immediate vicinity is clear. You should be able to just see his head peeking out if you're standing by the wall across from the stairs.
With the second sniper down, head up the stairs when the way is clear and collect the fallen sniper's weapon for more ammo. Take cover at the top of the stairs, pick up the acetylene tank there, toss it at the enemies below and shoot it to hopefully kill a couple of officers in the blast. Keep an eye on the stairs, as an officer may have come around to try to take you down.
There will be a third sniper on the walkway at the far end of the yard. Take him down with your rifle when you're no longer under fire. When the third sniper is down and the area below is clear of enemies, scour the area for ammo and look around for a gas can. Pick up the gas can before moving forward.
Taking out the snipers
Be ready when you enter the tunnel, as another batch of officers will appear at the other end. As soon as these officers appear, throw the gas can toward the other side of the tunnel and shoot it once it reaches them. Get behind cover and use your shotgun and rifle to clear out the remaining enemies before pushing forward to the next area.
Climb the fence beyond the tunnel to complete the chapter.