I did another test yesterday evening :
BC2 : 1'41"95 - 42 coinsI don't avoid the 2 last bumps. 1'41"xx can be done without mistake.
MC3 : 1'33"86 - 36 coinsA ghost over me in the last lap... No sandboost at all, 1'31"xx could be possible without this ghost.
KB1 : 0'52"96 - 43 coinsAll the race was done with slides, a better time is possible, but 0'52"xx is already very good.
CI2 : 1'10"76 - 29 coinsA ghost over me in last lap... 1'08"xx was possible without it.
Total of 150 coins and 3 stars... I look at Chikoritachu's differents times, and I think your worst course is MC3. I think you haven't trouble at BC2, can you do some laps under 20"30 btw ? For MC3, under 18" is possible without sandboosts. But if you can down some laps under 18"20, it'll be already a good point. KB1 I did a few laps under 10" but slides were very tight... I think you have to do under 10"50 regularly. CI2 is hard to maximize, I remember I did a 12"99 once, but laps under 13"50 are already excellent. Try to do some laps under 13"70 here.
If you can do all these times, and do a Cup without any mistake, I don't see how you'll be able to avoid *** the next time !