Hide drum instruments on a GM drum map?

Is it possible to actually hide instruments on a drum map? For example, I’ll never need a cowbell, bongo, whistle etc. It would be great to limit it to only the drums I need.

This is possible when you save a new drum map and edit the xml file produced as a result.

You can also move the kit pieces you want together at the top of the map without changing their assignment. Learning to use the drum map is highly recommended. Some very useful functions in there.