G'day waynee, welcome to GPSPower.
The Garmin Cyclops GPI files are encrypted so not easy to de-compile them.
Other 3rd party files without voice warnings can usually be separated into their underlying location [GPX/CSV] files and then recompiled using POI software with a compatible sound file [WAV/MP3] suitable for your unit. Have a look in the [Only registered and activated users can see links. ], scroll down to 'Working with pois and favorites' and the [Only registered and activated users can see links. ], scroll down to 'Pois Management Tools'.