To gain an extra boost, press either R3 or L3 during gameplay, and you will get an extra boost.
Complete the game and load your completed save file from the title screen to begin a new game. You can now use an overweight AC.
Successfully beat the game save then load your data. You can now access 3 new high paying missions. After defeating all three you will get very fast hover legs and an inside orbit cannon.
(You can go overweight into these missions.)
Load Info From Original AC2:
Load your saved game from the orginal Armored Core 2 game into the One Player Scenario to start where you left off before the expansion. This, of course, hinges on the fact that you played and saved a file from the original.
Steal Your Enemy's Emblem:
In the single player Arena mode you can steal your defeated opponent's emblem. To do this you of course have to beat an opponent in the Arena, then once beaten you can go back to the opponent selection screen where everyone is ranked by number. Highlight and select someone you have defeated and then press START + SELECT and you should hear a sound. Press the two buttons again and again until you hear the sound. Once you hear the sound go to the Edit Emblem screen and the emblem selected will be the one you just took from your opponent. You can then edit it or just wear it as your own.
When you begin the "Attack the Airbase" level you should land on a rock outcropping with a landing pad on it. Go through the door next to the landing pad and defeat the enemies. Go through the door and you will see a hallway. Go through that hallway and you will see a door. WARNING there are some flying MT's right behind the door, kill them quick. Go over the huge gap by using overboost and jumping. If you get to the other side do not open the door, it is locked. Look to your right and you will see an outcropping like the one in the beginning. Go to it and open the door. You should see an elevator. Go up but face the switch. When you get up look about 100 degrees to jour left and there will be two boxes next to each other destroy them and get the part by pressing circle. It is a missile interceptor extension. NOTE you have to buy it in the shop, you don't automatically get it.
To activate the Limiter Release, press L1 + L2 + R1 + R2, then press R3 (Overboost). This will put you into Limiter Release mode for around 40 seconds. The only down side is that you get an OB Depletion indicator after the 40 seconds are up, leaving you totally powerless for 50 seconds.