Effect of non-registration of documents required to be registered
No document required by section 17 1*[or by any provisions of the Transfer of Property Act, 1882 (4 of 1882)]. to be registered shall –
affect any immovable property comprised therein or
confer any power to adopt , or
be received as evidence of any transaction affecting such property or conferring such power, unless it has been registered:
1*[Provided that an unregistered document affecting immovable property and required by this act or the transfer of Property Act, 1882 (4 of 1882), to be registered may be received as evidence of a contract in suit for specific performance under Chapter II of the Specific Relief Act, 1877 (1 of 1877), or as evidence of part performance of a contract for the purposes of section 53A of the Transfer of Property Act, 1882 (4 of 1882), or as evidence of any collateral transaction not required to be effected by registered instrument.]
Please note that this proviso is applicable only to Specific Relief Act 1877 and not to the Specific Relief act 1963 Thus buy a plain reading of this provision, it is clear that registration is compulsory as per Sec 17 (1A) of the Registration act 1908 as amended by Act 48 of 2001.