Download Custom POI Files From GPS

http://www.gpsbabel.org/capabilities.html

In your situation, I think I would just re-download all of the files and reload them.

That would get you the most current locations.

Further, you might just decide that there are some other POI files that would be a good addition.

In the upper right hand pane of this site (just under your name) there is a link to "My Favorite Files". If you click on that link you will se a list of all of the POI files that you have previously downloaded. You might say, well I don't want that one any more and not do another download of that particular file. However, you will see others that you still want. Maybe, since you last downloaded files, you have found a new restaurant that you like and would want to be able to route to on trips. So you would add that to the list.

There is this great piece of software called POISync.

What you do is to start the program and it asks you for your poi-factory id and password. Once it makes the connection to poi-factory.com, you can click on the "Add Files" button and a list of your favorite files will appear. From there you can have it do some batch downloads.

Everyone ought to check out POISync by looking at the thread
http://www.poi-factory.com/node/26847

Unfortunately, the links to where Schumans (one of our members) once hosted the software are all broken. I emailed Schumans and he sent me a newer version than the one I was running (although it did fine and was not broken))

Once again, Boxcar nailed it. I converted my McDonalds.gpi to a Mapsource file using GPSBabel just to see.
The Mapquest file can be saved as a GPX.

same problem with me

Sorry, obviously didn't make myself clear enough.

Which file contains my custom POIs in a nuvi 855?

A file that ends in .gpi

Personally, I would advise to redownload the files to make sure that you have the current versions.

It probably wouldn't take any more time than converting the GPI file.