The four numbers following the gauge name are for position and size on the panel. The only way to edit the brightness is to edit the gauge itself. If they're written in XML, you can extract them from their cab file and possibly locate a line in the code that you can alter. To get the file back into a cab, you would need to extract the entire gauge to a folder, then use the cabdir.exe included with FS to recompile the cab. On the other hand, you could just leave everything in a folder instead and FS would be able to load the panel a little quicker at startup. If the gauge is part of an older style *.gau file, you won't be able to edit the code without some way to decompile the C++ source.