Maximum money:
Press [A, B, C] six times, then press L in the options screen. The sound of a missile will confirm correct code entry.

Level	Password
2	HD6S?KBILKL5KHRBM
3	WPNS44943LXKMWGM
4	HPWSPFH77L2KRWVL
5	3MSCWFY?TSTWZYSP
6	8V!DM8F78HZJHSPL