Sebastien, you can plug the GPS directly in to the Mychron 4 and not even use the data hub. The downside to this is you nuke the 9 volt battery in the Mychron very quickly, whereas the data hub method requires you to connect to an outside battery. I’m paranoid about running anything off of my kart’s battery, so I just use the direct plug-in method and carry a bunch of extra 9 volt batteries around in my toolbox. Tony’s example really is the best; the data hub is handy to have and makes downloading data and uploading track maps much easier. This winter I’m going to figure out a way to mount an RC car battery somewhere to power it. Most people claim it’s fine to run off of the kart’s battery, but I’ve had a few battery related issues and don’t want to take a chance.