Vatchern, I think I already know all the shortcuts in the game.
Alright, time for a breakdown of each track.
A lot of this is made easier by video samples found on Archi's site:
http://membres.lycos.fr/archismk/
DP1 Crash your kart against the wall, and jump at the time of collision in such a fashion that you such skip a lap by returning over the finish line.
Also works on KB2, MC4.
GV1 If you go at top speed you can quite easily reach the ledge towards the end with any character on 150cc. If you shroom before the bumpers, you will gain A LOT of height.
BC1
See animated videos at /archismk/ link.
Also, you can skip a wall by using a feather, if you swerve after the boost arrows on your left.
CI1 Look at the fast lap strategy used in 4"XX PAL lap video.
Otherwise on this course, shrooms are useful for the bumpers. If you land from one bumper directly onto another, you will maintain speed until you touch ground.
GV2 See RR finish line skip video on Archi's site. I think the method is the same.
Also, You can curve all the way around the first turn and use a shroom to reach the extension of the finish line in mid-air. (I don't think feather works, but I haven't tested, since I suspect this one just as the BC2 shortcut, might be NTSC only.
DP2 Might be possible to skip a wall like on DP3, I'm not sure about this.
BC2 Use a feather to skip over the lava at the dead end (STOP). Look at Archi's site for the big SC, preferrably used on last lap.
KB1 There should be a video of the water trick on Archi's site. Otherwise, just shroom over the narrow part of water after the small island with an item box. Might work well to release the gas as you hit the water if you shroom it, to lessen deceleration (works in MK:SC for GBA).
CI2 This one is easy, big and requires a feather.
Again, look at the emulator animations on Archi's site.
VL1 The same finish line shortcut as the BC1, on the left side.
BC3 Archi's site..
MC4 See DP1
DP3 Archi's..
KB2 Archi's.. and see DP1
GV3 Archi's.. there's also another one that is inferior since you have to break blocks, and you can use the RR finish line method instead.
VL2 Water trick..
RR Archi's..
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http://smkwr150.chez.tiscali.fr/index.php3
This is the site for 150cc. records. It has some nice videos with the shroom long boost.
Also, I'll search around for information on the long boost in MC2 in time trial by the jump, and try to find link to pages on the normal boost that can be used to cut over offroad surfaces, and edit them in when I find them.
Edit:
Normal corner boosting:
http://www.geocities.com/sim07laflamme/boost
Here's a good MB topic on the boost in MC2. :
http://www.mariokart64.com/cgi-bin/yabb/YaBB.cgi?board=SMK;action=display;num=1096308118
I'll say, though, that for last lap in MC2 150cc., you should trigger a normal boost at the jump, you don't even need to use NBT boosting, just a tight corner before the straight, and cut over a bit of the "offroad box" to the left with a jump, the boost you built up before the jump should last you through the sand.
Andreas