With an 80 percentile in JEE Mains and 63% in board exams, you have a reasonable chance of getting admission for Computer Science in some Mumbai colleges. However, the low percentile in MH-CET (3.99) might limit options in state quota seats. Here are steps you can take:

• Apply through JEE Mains : Use your JEE Mains score for national-level institutes and private colleges in Mumbai.
  
  
• Look for Private Colleges : They often have more flexible admission criteria.
  
  
• Counseling : Participate in both JEE Mains and MH-CET counseling.

Check individual college cut-offs and admission criteria for precise details.

I hope this answer helps you. If you have more queries then feel free to share your questions with us we will be happy to assist you.

Thank you and wishing you all the best for your bright future.