I state that I do not know how does the Montana,sorry I assume that it behaves like a nuvi automotive

For testing,try the bouquet precompiled in GPI for SCDB (France,of course)....and test for icons BMP. [Only registered and activated users can see links. ]

If they work at least icons, you can try the GPX, the BMP, and WAV files (from bouquet GarminHeaven) always SCDB

If you prefer,you post the files association (i.e. namePOIsfile.gpx with namesoundfile.wav) sound and I'll get ready the GPI

Bye,bye