Wait until the 'Press Start' message pops up on the screen, then push C Left, C Down, C Right, C Up, C Left, C Right and C Down.
Pressing R on the select aircraft screen in all the modes but deathmatch will your plane a facelift. In deathmatch mode, you'll need to hold down R and select one of the four default aircraft.
For each level you complete in the normal game, you'll gain one enemy plane for use in deathmatch mode, up to a total of six.
This is fairly straightforward, you just need to complete all bonus missions and Spanky will be yours to command!
To be honest I couldn't get this one to work, but maybe you'll have better luck. When the start screen appears, on controller two push and hold Up on the d-pad, then press R, L, Z and C Down simultaneously. You should now supposedly be able to play with extra vehicles on a new track.
Ah, the world's least intuitive and player-friendly turbo function! If you need extra speed in the race, hold down A to accelerate, make a hard turn in either direction while holding Z, then release both buttons. If by some miracle you've got your timing right and haven't sent your car into a wall, you'll get burst of extra speed. You can keep using the turbo until the temperature gauge rises too high.
Hold A and B while you're waiting at the start, then release B after the announcer says 'Ready!' to get a much-needed turbo start.
Hold L + R + Z on controller two before the title screen appears. Keep those buttons held, then quickly press and release Up
+ C-Down on controller two when "Push Start" flashes on the title screen. Then, press Start on controller one before the title
Note: The timing of this code is particularly sensitive; all buttons must be pressed and released at exactly
the same time as indicated.
• Points: press Square + Triangle + Square
• Power Up : press Circle + Triangle + Square, X when in danger
• New Life: press Circle + Circle + Circle + Triangle + X + Square + Circle + X
• Level Jump: L1 + Square