Changing output format of displayed body text I imported node and comment body fields as "Full HTML" (they are coming from a trusted site).

Now I want to display those body fields differently, for example strip certain HTML tags. Do I just change the filters for "Full HTML" and use "Full HTML" as my "custom" input format? I could change the name of it, just want to make sure it have special significance in Drupal.

Or do I have to manually change them in the DB?
You can safely make changes to the regular "Full HTML" filter. It has no special significance in the system. It is simply created by the "Standard" install profile because it is convenient for end users. If you install a minimal profile you won't have it at all.

Obviously changing the full html filter will affect other nodes as well that use this filter.