MBBS seats are fileld at 2 levels; All India Counselling and State Counselling. Now All India Quota has 15% of seats allotted from State GMCs, Deemed/Central Universities and IP Quota of ESIC Medical Colleges. State Counselling has 85% of GMCs, Private Medical College seats. Now cut offs for each College, each State vary at All India Quota level and State Quota level. For example, if you belong to West Bengal, Tripura, Karnataka, the cut offs for SC Category will be relatively lesser than when compared to States like Tamilnadu, Delhi, AP, Rajasthan, HP, Bihar, etc. And cut offs change every year depending on the no.of Candidates appearing for the exam, no.of Candidates qualified, top NEET score and difficulty of the exam. Considering all these factors, your target should be nothing less than 550.