Originally Mix FM 91.0MHz from Gunung Jerai still can be received in Balik Pulau, but signal is not so strong enough due to the area consists hills.
Balik Pulau is just like Penang version of Cameron Highlands.
Since Mix FM 91.0MHz is the commercial radio station in Malaysia and Mix FM won't launch another transmitter there (also the rural areas) due to no commercial values gain, Mutiara FM must not use same frequencies with commercial radio station from Gunung Jerai, Bukit Penara and Bukit Larut, instead must reach 200kHz from the particular radio station.
In addition, there is another RTM radio station Bukit Genting which co-channel with Gunung Jerai, there is Nasional FM 93.9MHz and Mutiara FM 93.9MHz, but both of them are RTM radio and they have different target locations.
Mutiara FM 93.9MHz does not cover whole Penang states, but only cover Batu Feringghi, Tanjung Tokong, Tanjung Bungah and North Seberang Perai only.
Since Mix FM use 91.0MHz in Gunung Jerai was earlier than Mutiara FM 90.9 and Mix FM covers whole Penang states with 91.0MHz, RTM Mutiara FM SHOULD migrate its frequency away to suggested frequency 100.7MHz. So, Mix FM can be received in Balik Pulau and Mutiara FM Bukit Genting 100.7MHz will be more stable than 90.9MHz.
100.5MHz: Nasional FM Gunung Jerai
100.7MHz: Mutiara FM Bukit Genting
200kHz OK.