I had almost forgotten how some Shrapnel players love to "tinker" with the game files.
The first and Last name files can be changed, as long as you keep the same number of names in the file, and keep the text formatting the way it is. The existing names themselves can be changed fine.
The graphics can be changed, as long as you keep them the same size (200x150 for the byte pictures, and 75x75 for the gang pics, otherwise they might not look good) and the SAME file name and extension (.JPG). Aside from that, the pics themselves can be changed freely; they're not encoded in any special way.
Have fun and I hope the Thunder Pack has won you over!