I tried every of the 80 sounds in the GENERAL.SBK and now created a list of which sound is what:
80 Amount
321.pcm 3,2,1 sound or Kahuka's honk
block.pcm sound when sth. hits the shields
brake1.pcm brake of player
brake2.pcm brake of player
btmout.pcm hit sth. hard
canhit.pcm hitting bullet e.g. in Race 2 of Basil's Circuit
cansht.pcm launching bullet (not from player or opponent)
cansus.pcm Basil Race flying bomber at end-sound
cursehit.pcm curse while driving
cursesus.pcm curse of mummy 'gate'
engine.pcm player's engine
enhan01.pcm collected 1 white brick
enhan02.pcm collected 2 white bricks
enhan03.pcm collected 3 white bricks
form.pcm Respawn of power ups
go.pcm GO!-Sound
gpwdrdrp.pcm two vehicles scratching with their sides against each other (thanks to RobExplorien)
gpwdrsus.pcm Yellow and 1 White: flying backwards
grphit.pcm grapple Metal Hit
grppull.pcm grapple pulling
grprel.pcm another sound of grapple
grpsht.pcm throw grapple
grpsnap.pcm Metal grapple Fail
grpsus.pcm another sound of grapple
hitcar.pcm car hit sound
hitenv.pcm ANother hit sound
horn01.pcm Player 1 Honk
horn02.pcm whistling honk (high-low)
horn03.pcm Player 2 honk
horn04.pcm Old Honk with Kinda Fail
horn05.pcm Old working Honk
horn06.pcm Redbeard's Honk
idle.pcm player engine in idle position
mdrop.pcm place 'Yellow with 2 White bricks'
mmine.pcm 'Yellow with 2 w. bricks" tractor beam sound
mtrap.pcm caught in tractor beam
octact0.pcm Green (0 white) startup
octact1.pcm Green (1 white) startup
octact2.pcm Green (2 white) Startup
octact3.pcm Green (3 white) Warp sound Startup
octexp0.pcm green (0 white) extinguish
octexp3.pcm Come out of Time Warp
octsus0.pcm light rumble sound, Belongs to Green0
octsus1.pcm light rumble sound, Belongs to Green 1 White
octsus2.pcm flying rumble sound, Belongs to Green 2 White
octsus3.pcm belongs to TimeWarp, same as octsus2
oildrp.pcm drop Oil (yellow0)
oilhit.pcm opponents slipping on oil
oilsus.pcm oil bubbling
power.pcm drive through time warp
rockhit.pcm rocket (red, 3 white) hit
rocksht.pcm Rocket launching
rocksus.pcm (Rocket flying sound) Unknown to me
shield1.pcm Blue 1 white shield sound
skid.pcm Unknown Sound???
skrcar.pcm Dangling car sound (fast hits)
skrenv.pcm Another Car hit sound
slide1.pcm Powerslide start
slide2.pcm Sliding sound
soff.pcm Shield fade out
spin.pcm Player on Oil or sth else spinning around
sput.pcm Deceleration sound (thanks musiclover350)
start.pcm Player engine startup
tire1.pcm friction of wheels with surface, resulting in a screeching sound (thanks to RobExplorien)
tire2.pcm friction of wheels with surface, resulting in a screeching sound (thanks to RobExplorien)
turbo.pcm Sound when opponents drive into Time Warp and tire sound when starting any turbo
wndexp.pcm wand going away
wndhit.pcm wand hitting
wndsus1.pcm Lightning active sound of wand
wndsus2.pcm Lightning passive sound of wand
block1.pcm sound2 when sth. hits the shields
block2.pcm sound3 when sth. hits the shields
enhbonus.pcm Exchange of power ups
grphtenv.pcm grapple failing
mrel.pcm tractor beam (yellow 2 white) fade out
octexp2.pcm Some sound belonging to green with 2 white bricks
shield0.pcm shield blue 0 white sound
shield2.pcm shield blue 2 white sound
shield3.pcm shield blue 3 white sound
eengine.pcm opponent's engine sound
One bad thing is that you can't change the sound of when you stop accelerating (so you put your hand away from Arrow up when driving). This sound seems to be hardcoded anywhere. Maybe anyone can find it?
A cool thing with the engine.pcm is that you can insert any other sound there (it has then different pitches, depending on how fast you drive). A cool engine sound is shield2.pcm or shield1.pcm and as idle sound use shield0.pcm.
The bad thing about that is the sound that is probably hardcoded and so you still hear the normal engine sound when stopping to accelerate (in german: 'den Wagen rollen lassen').
When you want to change some sounds, make sure they are placed there where you want to have them. For example you want to remove the player's honk and give him redbeard's honk. Then you write horn06.pcm where the player's honk is set (horn01.pcm). So you just change horn01 to horn06 and then you recompile, ...