In exploring the new features of Civil 3D you may have noticed that there is a little utility included with the product that allows you to edit the default catalog. As you may or may not know, the catalog is contained in a SQLITE file in the same location you would look for garvity systems on a default install:
C:\ProgramData\Autodesk\C3D 2013\enu\Pressure Pipes Catalog
Opening this file you will see all the available parts in the catalog on the left. Clicking on each one will show the available parts in the widnows on the right. Notice that there are some values missing from the columns. These can easily be manually added and customized as necessary. Simply double clicking in the cell and adding the value will do the trick. This will allow you to add information such as manufacturer, coating SDR, schedule, etc. as you see fit. All edited information will be available to be pulled by Civil 3D label styles once edited.
You may also find that inner Diameter is missing from the pressure pipes in Civil 3D. If this is something that you require in your labels and design, a quick and simple edit is all that is needed in order to have them display.