WarHammer 40K - Chaos Gate

First, go into the Data file in the game directory.
Then, you can edit any of these files to change certain
aspects of the game, such as:
Names for both sides, weapon statistics, experience
awarded for kills, vehicle statistics, Psyker power
statistics, and more! All you have to do is edit the
files.

These are the ones I have found most useful:

Accounting.dat - Experience
SpellDef.dat - Psyker Powers
VehicDef.dat - Vehicle Statistics
WeapDef.dat - Weapon Statistics
UltNames. - Ultramarine Names
ChaNames.dat - Chaos Names


Note that any changes you make may effect Chaos as
well, so be careful, especially with the weapons!