C4 version 1 mutator. created by the dev team located in this website.
http://war.unrealism.com/

-How to install
Extract all the files included from this zip archive to the SYSTEM folder that is located in your UnrealTournament install.
There are several C4 mutator available and some options in the MOD menu and some new gamemodes.

Have fun.

-Advice
I suggest you to download an install the mutator named WoRM 190. (you can use StuffSwapper, but i think WoRM is better).
It is a very interesting mutator to make your prefered C4 weapon replacement selections, due to the big number of weapons included in C4 version 1. 

WoRM. is created by Kangus and was available from Weapon Of Destruction
http://www.planetunreal.com/wod/worm/files.htm
It can be downloaded from there too
http://www.levels4you.com/download.l4y?file=5413
