Hey guys, I was checking out the website for the WMClan, who run that Viper DM server, and they had this Aiming Tweak for UTInput.ini. I'm not sure it makes a huge difference but it does seem to make the mouse feel slightly more responsive.
Hopefully no one minds me reposting it, all credit to them, or whoever came up with these tweaks.
(Found on their site here: http://www.wmclan.com/Page3.html)
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Remove the "laggy" mouse feel and make it like in UT2004
Find in: My Documents\My Games\Unreal Tournament 3\UTGame\Config\UTInput.ini
[Engine.PlayerInput]
LookRightScale=0.000000
LookUpScale=0.000000
bEnableMouseSmoothing=False
Bindings=(Name="MouseX",Command="Count bXAxis | Axis aMouseX Speed=2.0",Control=False,Shift=False,Alt=False)
Bindings=(Name="MouseY",Command="Count bYAxis | Axis aMouseY Speed=2.0",Control=False,Shift=False,Alt=False)
...
Bindings=(Name="LookUp",Command="Axis aLookUp Speed=+25.0 AbsoluteAxis=0",Control=False,Shift=False,Alt=False)
Bindings=(Name="LookDown",Command="Axis aLookUp Speed=-25.0 AbsoluteAxis=0",Control=False,Shift=False,Alt=False)
...
Bindings=(Name="GBA_TurnLeft",Command="Axis aBaseX Speed=-40.0 AbsoluteAxis=0",Control=False,Shift=False,Alt=False)
Bindings=(Name="GBA_TurnRight",Command="Axis aBaseX Speed=+40.0 AbsoluteAxis=0",Control=False,Shift=False,Alt=False)
[UTGame.UTPlayerInput]
LookRightScale=0.000000
LookUpScale=0.000000
...
Bindings=(Name="MouseX",Command="Count bXAxis | Axis aMouseX Speed=2.0",Control=False,Shift=False,Alt=False)
Bindings=(Name="MouseY",Command="Count bYAxis | Axis aMouseY Speed=2.0",Control=False,Shift=False,Alt=False)
...
Bindings=(Name="LookUp",Command="Axis aLookUp Speed=+25.0 AbsoluteAxis=0",Control=False,Shift=False,Alt=False)
Bindings=(Name="LookDown",Command="Axis aLookUp Speed=-25.0 AbsoluteAxis=0",Control=False,Shift=False,Alt=False)
...
Bindings=(Name="GBA_TurnLeft",Command="Axis aBaseX Speed=-40.0 AbsoluteAxis=0",Control=False,Shift=False,Alt=False)
Bindings=(Name="GBA_TurnRight",Command="Axis aBaseX Speed=+40.0 AbsoluteAxis=0",Control=False,Shift=False,Alt=False)


i found another tweak guide here: 
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