Once you fight with the cultists, go up to their alter. The Infusion upgrade is on it.

Grab the key from the Alter (Infusion #1) and run back to Lonsdown Residence with the key to unlock the chest in the small bedroom. Infusion upgrade inside.

The first time you use the Sky Rail, make sure to drop off at the Maintainence platform (it's blue, and to the left of the sky rail). In the back room is an upgrade. Don't forgot to use the Telescope on the platform.

The second Siphon machine you come across, there is a desk infront of you with a Voxophone on it. Behind the desk is an Infusion upgrade.

After the fight at the ticketing office (ouch, that hurt), run around the back of the office and take the Infusion upgrade.

From the welcome hall, look to the left. You will see a locked door. Behind the door is a Voxophone and Infusion upgrade.

Get the code book from the Ticketing building (cannon) and go over to the other building to unlock the secret room. Inside is a Voxophone and an Infusion upgrade.

After the ambush, go into the right hand room where the soldiers came from. You will find it on a bench

After the second courtyard battle (you're on your way back), go into the room to the left of the message written on the wall infront of you. Infusion upgrade in that room.

As you board the Zeppelin, enter it, and go to the desk on the right before you set off. Find the infusion upgrade and some other stuff (money, etc).

As you come across where Elizabeth is being held, you will be above a courtyard with two men in stockades. On the other side you will find some prison cells past a door. Inside on the floor, by the bars, is an upgrade.

When you come across an office that needs 5 lockpicks to pick, do it. Infusion upgrade inside.

On the bottom level of the club, find the dollar machine at the back. In the adjacent room is an upgrade.

Use the code book you find in the Good Time Club to open the hidden doorway inside a locked building. (Alley leading onto some shipping crates, behind main plaza.)

As soon as you enter the town, go to where some thugs are. You will need to fight them to get past to the upgrade.

Go up to the first floor, and turn left. You will need to open the room.

Go up to the first floor, and continue around past the Med Kits tear. Turn left and go into the furthest office. Open the chest with the key you found in the basement of the Graveyard Shift bar (Shanty Town).

After the story plays out with the two characters, open the doors on the left and right before proceeding forward into the recently opened door.

After picking the lock to the building, head left and pick a gate open. Upgrade in there to the right.

Requires you to collect Voxophone #56 and #57 to unlock a switch in the Salty Oyster bar. Hit the switch to open hidden room.

In the Lutece lab, upper floor bedroom. At the back.

On your way to the financial district, make a left into the red shop called Wilson Bros. In their shop they have an upgrade (in the window display). When you pass Hudsons (you will see graffiti that reads Founders will bleed), go inside to pick up the code book next to a sink.

From the bank floor, looking at the big vault door, take a left and follow around until you find the graffiti. Use the code from Hudson's store (Downtown area) to open the secret room.

After you rescue Elizabeth, pick the lock on the door opposite to where you need to go. Up the stairs will be an upgrade and Voxophone.