Sir i am getting 178 in advanced ,got 91% in cbse and 208 in mains general category ...sir i want to have mechanical , or electrical ..i think i will be getting chmical engineering or so.Should i drop,cause i am surei will get around 500-1000 rank in iit next year.

If you are confident of performing really well in JEE next time, dropping is a good option. Otherwise, I will suggest you to join any of the good NITs and side by side prepare for JEE for the next year if this is possible.
Thanks and Regards
Apoorva Arora
IIT Roorkee
askIITians Faculty