1.
This is difficulty where can spawns special forces on places where on other difficulties is noone (for example 4 buldozers in vault = First World Bank, 4 Shields where you are escaping = Green bridge etc.)
2.
On this difficulty you can be 2x down at 3th time you have only 1 second (you are exactly in custody), so If you were 2 times down, take a medic, but If you were down for example 1 time or never, don´t take from medic. If you are in good cover you can be 1-2 down and than take from it. This will help you don´t spend all medics at start of game.
3.
Don´t take stupid crew bonuses like Accuracy, Speed reloads or Mr Nice Guy and stupid equipment like Sentry Guns or B9 pistols. You need health and ammo, that´s all!
4.
When is someone in custody, and there is end of assault, you have only few seconds to trade him. You will probably need police hostage. Here´s some tips:
Heavy Swat - 1 shot to head with M308 + F, F, F = he should give up
Security Guard, Cop or FBI agent - 2 hits with melee + F, F, F = he should give up
Heavy Swat - 1 shot with Bronco 44 to body + some melee hits + F, F, F = He should give up

Loadout
Well, one of the easy maps on this difficulty. First, loadout. You should take on each map 145+ difficulty (if you are 4) 2x Big game hunters and 2x Agressor crew bonuses, 2 ammo and 2 medic bags and extra start out ammo. It´s up to you which weapons you take, but I recommend Bronco 44 (pistol) and GL granade launcher (secondary). On this map is best AK (primary weapon) or Brener machine gun.

Heist
You start normaly, find manager, tie him or shot him (I don´t recommend shot him) get card etc. When you place drill, all players go to managment (manager´s room) and stay there. Just camp there and kill police who get into managment. When drill jams, 1 player run to repair it by way near server room (not by cafeteria, lobby etc.) Other players can cover him at the start but DON´T GO WITH HIM. Stay in managment. Running player should have clear way (maybe 2-3 Cops) and only enemy in drill area should be snipers (player who is repairing drill = runner, shoudl have M308 or Compact-5). When he kill them, he can easy repair drill and get back to managment. Other players are still in managment and covering him when he is comming back. This repeat again and again when drill jams. When you finish drilling, all 4 players move to valut hallway by the same way like "runner". Kill the security guards (if they spawn there) and 2 players with thermite will put it. When you are melting the floor all players go camp in 4 holes before valut hallway. Here´s the picture:

Camp here untill thermite melt floor. You should have still all 4 bags, you can drop 1 ammo and 1 medic bag here in that holes. If you have only 2 bags drop it here.

Vault
When you finish melting you can go into the vault. Now the hard part: In vault are 4 BULDOZERS. 2 of you can go to vault and 2 stay in holes (if you feel on it) But I recommend all players to vault. If you are 4 there you should easy take that 4 dozers. Kill them and take money (if you save 1 ammo and 1 medic, drop it in vault and use it) When vault doors open you have 2 tactics: If you have low HP and low ammo you should use tactic 1. Running :), just running to holes and use medic and ammo. This tactic you can use always but there´s risk that someone will be in custody, cause you can´t get back for him. The second tactic is not too slowly but not too quickly go away from vault and shooting cops around you. If you have enough HP and ammo you should survive. Get to the holes and use your bags (if there are any).

Escape
Now the tactic is simple. Run, run through the lobby, through cafeteria, upstairs to the hole with C4. If is someone down and you can help him, do it! If not, leave him. Sometimes there are few shields in lobby or couple of snipers at the balconies. If there are snipers I recommend just running. When you place C4 and blow the wall, go into it and clear this rooms (you can also run through it but It´s not very hard here and you could lose someone when running). Here can spawn dozers or tazers with few heavy swats. When you clear it and get on stairs there are tazers on it EVERY TIME, so you have to kill them (easy when you are 4, but if you are 1 or 2, kill them carefuly and don´t get tazed or don´t run through it). When you are down, in final coridor there can spawn 1 buldozer (he will kicked door) or 1 tazer (the same) or 1-2 cloakers at the end from left side (This is only 1 or 2 enemies, so you can just run near them). So, you got it ,first map on 145+ and also achievement Bank on me.

Loadout
Classic loadout for each overkill 145+ map (2 Big Game Hunters and Agressors, if you haven´t DLC you can take 2 more blood to bleedout, extra start out ammo, Bronco 44. and GL granade launcher)
And now for 1. tactic 3 medic bags and 1 ammo and 1-2 players should have M308 or MP5 for snipers, 1 guy should take Brener or Reimbeck shotgun.
And for 2. tactic 2 ammo and 2 medics and also some players with M308 (2-3 are good)

Start
Start it always the same. Open door and run. Just run through streets and don´t stop. Don´t shot any cops and if is someone down, leave him (you will can trade him later).When you reach 2nd crossroad you have to decide which tactic you will use.

Tactic 1. (camper)
If you are doing tactic one take loadout for it. This is very very easy tactic but it is a kind of glitch we can say. The most important is 1 guy with Brener or Reimbeck (also can take AK) and medic bag. This guy should be a player who have this map done on 145+ becuase he probably will be in custody at the end. You are still running and when you pass 2nd crossroad (the place where Bruce with his car have an accident and he break a hydrant) you take a right way and still run. 3 other players will still running to objective and that 1 important guy will stop, get camp and place medic here:

He will be there all the time. Just for keeping cops there. Sometimes some police can get into this "stronghold" and he kill them. Other cops should just shoting to wall behind him. When you are running 2 of the other 3 guys can be downed, leave them but this guy must survive and get to his place. When you reach objective (Matts crashed car) you can play it like normal like on other difficulties, just stick together and trying to survive it. Why? Well, that 1 players will keep there almost every police members so you will have minimal problems to make your way with Matt etc. You can continuing like in 2nd tactic to the end. When you will have to escape, this "camper" will just suicide himself and you escape. You can also try to trade him, but I don´t recommend this, cause you can miss a time for escape.

Tactic 2. (normal)
Take loadout for it, and play it like tactic one, but all players are running. Noone stay camp, again 3 of you can be downed if 4th player reach objective. That 4th player will trade that other 3 with civils there.
Now this will be hard without camping glitch in tactic 1, so I recommend tactic 2 only for skillers. You all camping here:

Behind that green container is small space to camp, all players go there and cover themselves 2 for each side. You can drop 1 ammo and 1 medic bag here. You are just killing the cops and slowly moving for thermite (If you are afraid you can do it after assault each time, but this takes too long). When is Matt out, you can push him at that moment or wait for end of assault but the best tactic is start pushing him 10-20 second before assault end. Here can spawn a few snipers so be very careful. It will be hard fight but if you reach the place where Matt stops (before stairs), take cover and you are 50% done. Don´t go very slowly, but not very quickly, just as Matt is able, maybe little slower. You will be sometimes down in this part. When Matt open door go slowly upstairs (Don´t forget Matt down, this is happening when I play with anyone every time :D). Now you reached place with few police cars and way is continuing to the left. If you are lucky, the door by your right side (when you are looking at cars) is open, 1-2 player go there 2-3 stay with Matt. Player(s) who went right side can kill all cops from right side and they stop spawning, if that guys will moving near police cars. Other guys will push Matt and cover each other again. If that door are close, you can only shooting and slowly moving up to cars to stop police spawning (very hard). Now last part of way, the way on the top. When you start, there comes some helicopters and 4 dozers will come. Just start moving back and kill them each other (here you will clever use M308 again). When you did this just continue up, where you can place your last bags (you should still have medic and ammo). The best tactic how to survive it is combination with "non assault". Camp behid police cars, (don´t go more up) and when there is escape just push matt and escape. If Alex go little back to get Matt, just push him little down, and cover each other. Now you have Hill street blues achievement and second 145+ map.

Loadout
Like I wrote many times: 2 Big game Hunters and 2 Agressors, extra startout ammo, Bronco 44... etc. 2 medics 2 ammo and 1 guy with M308 is important!

Start
Normaly, get in, start heist, find Chavez (in this part with gangsters try to lose no HP, they seems like easy enemies but they can easy get you down). I don´t know If this can happened on other difficulties but on 145+ they can wait outside for you. When they see that you haven´t money, they will attack you. When you find Chavez, get his key and open panic room, plant saws and quickly go check if this door are open:


Tactic 1.
If the door are open, you´re lucky and it´ll be very easy. This door goes to roof, so you don´t need to go by stairs outside. Plant saws in panic room. Now the positions of people aren´t very important but 1 rule: Don´t stay all together. I don´t mean that each player have to be alone, but don´t all be on 1 place. For example 2 guys can be on stairs between lobby and 2nd floor and 2 in panic room or 2 guys on 3th floor and 2 on 2nd etc. Because when you all be in 1 place, all cops will spawn there.
When you finish sawing, all move here:

Camp behind this sofa, you can drop all bags here (on it). Now that guy with M308. When you are waiting for something (wait for helicopter, C4 etc) you all stay here, and just killing cops who are in room. When there is an objective 1 player (with M308) go to roof to make it (first objective is take out snipers). He can go by stairs on right side to last floor, or by left side on stairs which is inside. He can decide or where is less cops. he will just run through it and through this door to roof. On roof are only snipers, he will kill them and run back to room where players are camping behind sofa. (The most important for this is doing it quickly, you don´t want to spawning cops on roof) This will he do every time like in objectives: secure the roof, kill snipers (when there is secure the roof, there won´t be any swats on roof only just on the tops of near building, so just kill them) Remember that other players must still be behind that sofa (or in that room) to keep police there. When you will doing everything like this, you reach escape, than just run down to lobby, down, and blow the door. Outside can spawn 1 buldozer and when you blow door there is couple of gangsters sometimes.

Tactic 2.
When the door to roof are close. The same loadout, but minimal 2 people with M308. You are doing everything like in tactic 1 untill saws finish their work. You won´t go camping behind sofa, You will be all the time together and moving around whole map. For example: There is comming objective secure the roof, you all go camp in a room somewhere on 2nd maybe 3th floor. Wait there until cops get there and you quickly move to roof where will be nobody (except few guys or snipers) This tactic is harder than 1st and if you are small level I recommend restarting game untill door to roof will be open, but Let´s continue. You are moving like this and helping ourselves, you can drop your bags on spots where are you often camping, but not all bags on 1 place. When you are going from down to up, sure you are using stairs, but If you are moving from (for example) roof or 5th floor to down you can jump on stairs outside, or If you think that you know it without bleedout you can jump from 1 window to another like this:

This you are doing still untill escape objective. Than normaly like in first tactic, just move down kill cops and finish this. Now you have achievement for panic room on 145+ and 3th map on this difficulty to Golden Masks.

Loadout
2x Big Game Hunters 2x Agressor, 2 medics 2 ammo, extra startout ammo, Bronco 44, GL granade launcher, and I really recommend here M308. Classic loadout for 145+.

Start
Start is normal, kill all guards and cops and plant all saws. The same as panic room, don´t lose much health here! Kill them carefuly but do it quicky, because assault is comming.
Now you have 2 tactics, but both are the same hard, it´s just different place to camp.

Tactic 1. (Hold your positions)
When you set all saws, stay camp behind this car:

Two players camp behind this car in the middle, 1 guy is behind car on left side and 1 guy is behind that white police truck on the right. You are covering each other, and holding your positions here. If you all will play together, cover ourselves and kill each cop who comes to you, you can survive. You can drop 1 ammo and 1 medic here. Fix only saws which are behind you, don´t go over this cars. If you find your guy in truck behind you, you are lucky. If not, just restart other saws after asault. When you got him, start move to tower after assault. You probably won´t have enough " no assault " time to reach tower, so just move him slowly or take a camp when assault comes. You can camp near containers (where you were spawned), stay there to end of assault or clear your way and reach the tower with your guy.

Tactic 2. (Last truck)
When you set all saws, stay camp behind last truck, like here:

You can also drop 1 ammo and 1 medic here. And just hold your positions here. Restart only saw on this truck. If your guy is in this truck, it is very nice. If not, just restart other saws after assault. Now the important part, when you got him, DON´T PUSH HIM! wait for and of assault. Than 3 players run to tower and get into it, but don´t go up, just stay in first floor and keep police there. The 4th player will stay behind that your last truck. When others are in tower, he will wait a bit and push your chinese guy to tower (he should have clear way, because other players are keeping police near tower). When you reach a tower with your guy, both tactics continues the same.

Tower
You are in tower, move chinese guy to the top. Drop your bags here. Now hold your positions here.
2-3 guys cover stairs and others take a look on plank walls (police can jump over it). Just kill them and don´t stay near 1 place where aren´t plank walls (there can shot you snipers from crane or building opposite to you. It´s not very hard to hold your positions here, if you get into the tower you are almost done, the part with saws is most hardcore. George will probably fail on first time, so he will return second time. Kill snipers on crane and building opposite to you and use a medic, take an ammo and run downstairs (you will be escaping when George will take your guy, just for save some time to escape). Just run, still run and when is someone down 1 guy help him and other guys cover him. Still run (sometimes there spawns some shields (4-5) just run near them or kill them with GL if you have it). if you start running before objective escape you should have enough time for escape and for survive. Near your final place to escape can spawn 1 dozer. Now you got achievement Beat the shield and 4th map on overkill 145+ difficulty.

Loadout
If you are going to make it on steath you can take B9 or Mark-11 but I don´t recommend it. You need it only for destroying cameras and you don´t have to destroy them. You can take classic loadout for 145+, but you won´t shot very much here, so just take 1-2 medic bags and 1 ammo. Everything other is up to you.

Start
Now you have 3 boxes. You can make it on stealth or loud. You´ll save a lot of time when you make it on stealth, but If you know ways of guards and you are skill in it, in this map, you can still fail it because on overkill 145+ are more guards like on other difficulties, so it´s a bit hard. If you fail stealth, continue is the same, but you will have to make boxes, so it takes longer.

CFO
The funny thing on overkill 145+ here is, that codes can´t work :), so if you made boxes on stealth you´ve just saved a time. You won´t make it whole on stealth. (Maybe it can works on 1% or what, but It never happened to me and I played that map a lot, believe me.) So make your "box" objective (stealth or loud, if you´re making it on loud, use the same tactic like with CFO) and get the codes. It won´t work so you will have to find CFO. Now the tactic: You are moving around whole map and just camp in 1 place, waiting for the police. When police reach your place, you just move to another spot. With this tactic you can make this map easy in 2. It is very easy. The best tactic is moving between this 3 places, because each of them have 3 ways to escape. (If police comes from 1 way, you can use second or third, sometimes police can comes from 2 ways at the same time, so use 3th way)

You can escape from here by stairs on left or stairs to down or way on front of you.

You can escape from here by stairs to up, or ways left and right.

And here you can escape by jumping down to gym.
This tactic you are using all the time. And when you find CFO just move him to roof and kill the cops. When you will moving with him, only few cops should be on your way.

Escape
This you can make all the time and when vault door open just steal the diamonds. To escape you need only to take diamonds in the middle of vault.

Loadout
Classic loadout for overkill 145+, 2 ammo and 2 medic bags. Good weapons: Brener machine gun, Reimbeck shotgun. In this map is good when everyone have different weapons.

Start
Nothing special, just stop the convoy, kill Murkies and move downstairs. Be careful, there will spawn lots of them, and also helicopter will come. The best is do it quickly but carefuly.

Tactic 1. (If there is meat)
When you come to slaughterhouse and truck will fall on its roof, you have 2 tactics. There can spawns meat or not. I mean pork, everywhere. If its everywhere use tactic 1, if there are only few pieces on tables use tactic 2.

Open truck and get there a drill. When you open the truck, there can sometimes spawns buldozer in it, so kill him. When you got it, place 2 bags (1 ammo, 1 medic) here:

Stay camp here, crouch down. When assault comes, just kill the special enemies, or cops who are too close to you. Now important part, you can fix drill when assault is in progress, but not normally. Fix it through the door, like here:

Clear the cops on your right (only few should be there, and cops from left shouldn´t shot you. Other players have to cover you from your camping place. Just fix it and quickly run back. If is someone still shoting you and you think you´ll die there, go back. If you are down there, 1 guy will help you, others cover him. Do this untill drill finish. When assault will end. 1 guy take 1 bag with gold (enough for now) and he will go place it. Others are still in cover, or you can take all gold and run together. If you run together place gold and quickly go back from thermites, and place them. If went only 1 guy, he will do it alone. You can decide which tactic you will use, I recommend 1 guy tactic if you have 1 good guy. If you are all beginers, go together.

Now you have tactic A and B.

Tactic A is just camp here:

Drop you last bags here and cover each other. When there´s an objective, fight your way, or wait for end of assault. This tactic easy works on OVERKILL DIFFICULTY but on overkill 145+ I recommend B tactic more.

Tactic B has the same start, camp at the same place and drop bags there, When police comes to you, just keep them there for a bit and when they start throwing smokes, move here:

Do the same, little camping here, when they starting to throwing smokes and there will be too many of them move to right. This you can make still around whole place with containers. Than just run back to you first camping place (near truck). Here use the same tactic, first camp near truck, than go to other side of slaughterhouse, just move around it and police will still try to catch you but you will be moving when they get there. Still do a circle and than move back to containers, do objectives etc. untill escape.

Tactic 2.
If there isn´t meat, go camp (and place 2 bags) in the kitchen, here:

Three of you will camp here (Warning! they can jump through that 1 window in the kitchen)
Just cover it here and keep police here. 1 guy, will be near truck, or he can be with group, and when drill jams, he will just go fix it. There should be only few cops. When drill finish, again, 2 tactics, together or 1 guy. When you move the gold and place thermite you will use again tactic A or B, It´s the same.

Escape
If you were using tactic A, just fight your way to escape container, if you were using tactic B, just fight the way or move around again. When you are escaping through conatiners at first turning to right, there will be 4 dozers, EVERYTIME, so just kill them and don´t die there. Now you got it achievement Lots of pigs but no pigs and also achievement for GOLDEN MASKS.

If my guide helped you or you like it please rate it!
If you have any questions or something is wrong, leave a comment!

Thx for reading this, I think I am going to write here also tactics for overkill 145+ on Counterfeit, Undercover and No mercy.