Please Help: Service tax on Restaurants

As Restaurants are covered under composite scheme of taxation ie @ 40% of value of goods and services supplied at therein. kindly guide whether for calculation of the SSI exemption of Rs. 10 Lacs we need to take only 40% value . Mean practically they need not to take registration and pay ST in case thier turnover be upto Rs. 25 Lacs . AS 40% of 25 Lacs = Rs. 10 Lacs Pls guide