Its not easy to complete stage 16 and 17 with Nimi.I beat those 2 stages and i will give some tips on how to do them with Nimi:
[For Four Dimensional Vertigo]
2.Do not get hit by ANY car.
3.Avoid MASHEENS,EL KINGS and DR Monstaas blows.(Not easy though)
4.Do not get hit by Radical One or Mighty Eight.
5.As for Sword Of Justice,always go around the checkpoint(if SOJ is gonna smash you away from the checkpoint)
6.Try to not crash into any Hazards.
[For The Mad Party]
1.Make INSTANT turns.
2.Avoid the other cars.
3.Keep your power to the MAX.
4.If the Big 3 are there,do ANYTHING to dodge them.Or else your wasted.
Hope these tips help you.