Haha... Japanese/Malaysian/Indonesian/Argentina RXZ 135cc are similiar in bodyset & engine. Except Indian, only 5 speed, and std exhaust version is available (1st RXZ generation).
Yes.. there was another version of RXZ >> RZR, only available in Indonesia and Japan. (with Fairing and gas shock absorber)
Phew... it must be very difficult to find parts in your country. or you can contact Indian dealers, maybe they can help
RX115, RXS, RX135, Indian RXZ have similiar exhaust design shape; and yes, apply racing exhaust will boost up your bike acceleration and topspeed