The voluntary retention route (VRR) cap for foreign portfolio investors (FPIs) will be enhanced by Rs 1 lakh crore to Rs 2.50 lakh crore, given the increased interest shown by them, Reserve Bank of India Governor Shaktikanta Das announced on Thursday. The enhancement of VRR, which seeks to provide a separate channel, broadly free of macroprudential controls, to FPI investments in government and corporate debt securities will be applicable from April 1, Das said.