Refer to custom Notification No.28 dtd 1st october, 2013
The Manufacturer produce at the time of clearance , a certificate from the head of the institution in the each case, certifying the said goods are required for
"research only"
and
the aggregate value of the prototypes received by an institution does not exceed 50 thousands rupees in a financial year.
in view of above"you have to maintain separate records and your are not eligible to avail credit on inputs used in exempted final goods. Other wise you have to pay 6% on assessable value.