Get an air gatling gun
Go to the pink tank and enter: GSASINRI

Get bound bomb
KKHWEEEE enter this at the pink tank

Q-nect CPU
There is a cave in the very back part of the snow region on the game. If you go into the cave , you get to do a special mission that gets you a secret part, but you have to destroy all these tanks and then a boss tank. If you win, go to Tughi and find a pink craftsmant tank and he will customize it into a CPU part for free. He usually is found on the first slope in the town.

Get grand flag
Go to the pink tank and enter ODGRITRO

How to get stuff for free
First go to the first town go to the heliport look around the place near the heliport
for a wired looking tank and talk the passwords are kwnohiro kkhweeee gsasinri
odgrttro

Got a FRIENDS
SQUARE.SQUARE TRIANGLE L2 L1

Cheat
Go to the ""suspiciocs looking tank"" and type in kkhweeee

Inside q-tein hidout
Complete all of the missons to get into the hidout

Kwnohiro=1000gold
Its simple just go to the pink tank in the first town and type in kwnohiro ok