Dear candidate warm wishes for such a good percentile in CAT. However as you know the IIT's bear the tag and hence their cut off criteria remains higher than the other. Now when it comes to your possibilities in IIT Delhi or IIT Madras, 89 percentile would somewhat fall short. But you have more chances in IIT Roorkee where with 89 percentile you do have good chances, and there are plenty other good private colleges, just check whether they have good placement records or not.

Good luck!!