The level of MHCET for engineering admissions is going to get tougher and at par with JEE from 2018. To help students prepare well for both state and national level entrance exams, the Maharashtra state government has decided to raise the standard of the state CET from next year. 

But you should not take the additional pressure of it right now and concentrate on your JEE Preparation because if you can prepare well for JEE Main then you will be able to catch up any level of MHT CET.

The syllabus will be your 11th and 12th.

Yes. This year DTE has changed syllabus and exam pattern of MHT CET exam.Now 20% weigtage will be given to Class XI curriculum while Class XII curriculum will carry remaining 80% weightage (40 Marks for 11th Class Syllabus and 160 Marks for 12th Class Syllabus).

But i would suggest you to prepare according to JEE syllabus and pattern becuase if you do well in JEE Main then you may get admission in india's top institute like NIT, IIITs and some other good national level colleges later you can get admission in IIT/ISM So aim for these institutes first.

If You are concerned about MHT CET preparation then there are not much difference in HSC syllabus of JEE Main and MHT CET but difficulty level and pattern will vary. JEE Main exam will condcut in first week of April and MHTCET conduct in the first week of May generally so you will have approx 30 days to prepare for MHT CET and if your JEE preparation is good then you can get good marks in MHT CET easily.
You can solve previous years paper of MHTCET (Solve majory HSC syllabus questions) and get familier with MHT CET exam pattern.

Focus on JEE Preparation now as only 5.5 Months are left for JEE Main exam.

Good Luck.