MP3 files

First, make sure you have an MP3 file not wav, ogg, wma etc. convert to mp3 if necessary.

Place the mp3 in the same folder with your csv or gpx file.
Name the mp3 the same as your csv or gpx file for example:
Redlight_Cameras.csv
Redlight_Cameras.mp3

Names have to be exact, the only difference is the extension...of mp3 or csv or gpx

Then use poi loader to load your files as you normally would.

Will this work for the nuvis that don't have the MP3 player (such as the nuvi 200s)?

I believe your unit has to be capable of playing MP3 fles before this would work.

MP3 must be a supported file type in order for mp3's to work.
In some of the manuals there is a section titled "Supported file types"
Some manuals make no mention of supported file types.

Dave4jp's c550 will support mp3's and is annotated in the manual
The nuvi 200 guide has no mention of supported file types. It does not have an MP3 player. One could conclude that mp3's won't work.

It would be interesting to see if models without an mp3 player (or listed file types in the manual) could support mp3 files to be used as audio alerts.

Perhaps users of these units could contact Garmin and request they add mp3 as supported file types so mp3's could be used as alternate alerts, and still not have an "mp3 player" to keep the units simple.

I uploaded the red light camera MP3 to my nuvi 200. Not only did the MP3 not play, it seems to interfere with the built in alert sound.

I think I will try it out on my C550 and see if it works

Trust me, if done correctly, the c550 will play mp3 sounds as alerts perfectly.