All Racers:
At the title screen press the following to unlock all characters:
R2(3)
L1
Triangle
L2(3)
R1
Square
Better Turns:
At sharp corners when turning lightly tap the gas which will make you turn sharper and slide less.
Towtruck:
In the special options screen play in Championship mode until you unlock Face Off 2. You have to defeat the Towtruck once to unlock it.
Gameshark Codes -
Master Code (Must Be On):
EC8783CC
1444403C
Unlock All Tracks:
3CA2154C
1456E7A5
3CA21554
1456E7A5
3CA2155C
1456E7A5
3CA21564
1456E7A5
3 CA2156C
1456E7A5
3CA215B8
1456E7A5
Infinite Turbo All Races:
4CADF902
145625DD
Unlock All Face-Offs:
3CA21574
1456E7A5
3CA215B4
1456E7A5
3CA215BC
1456E7A5
3CA215C0
1456E7A5