Oh, yeah I haven't examined DX's AI scripts but I didn't know they picked up on any other light other than flashlight. After all, DX has some of the dumbest AI ever...
Oh well, since DX is coded in a way that muzzle flash would affect gameplay , I guess there isn't much choice here...
Just release the mod already dammit!!!

Actually the problem with DX's AI isn't that it's dumb, but that it needs to be extremely clever. After all, most AIs just need to shoot you and flank you at most. Thief's AI is more sophisticated, but even that just has to patrol and figure out whether or not it should know where you are. Even Splinter Cell, with some of the most advanced and functional AI I've ever encountered, doesn't really have any non-hostile characters.

When DX's AI breaks down, it's generally in the intersection between states - going from friendly to hostile or the other way around. Going from not knowing where you are to finding you and attacking you. DX's AI has to do quite a lot of things. It manages to do many of them remarkably well, but it falls quite short of its own ambitions, and thus it comes off as spectacularly stupid while in fact it's significantly more intelligent than many other AIs. Half-Life's AI comes to mind - often praised in its day for its advanced combat maneuvers, it was actually 80% scripting and 20% bluff: It would shout out "flank him!" but never do so. It would rarely do anything it wasn't specifically told to do ("Spawn here. Take cover here. Throw grenade here. Advance towards here.")

So yes, DX's AI does some really stupid things, but bear in mind it only does so because the game demands so much of it

Actually, while they do perform a separate search for beams (flashlight), their search for you is based at least in part on your visibility, or lightlevel. Firing a silenced sniper rifle from darkness is less likely to expose you than firing a silenced sniper rifle that temporarily illuminates you rather brightly.

Also, I might be out of the loop, but aren't first person and third person models different? I was only talking about a nice flash in the first person view (the one rendered for your very own personal screen).

Well, the muzzleflash texture swapping is called entirely from code, and it also spawns a tiny light in front of you briefly to represent the actual FLASH (since the texture won't do that). I could of course recode it to draw a muzzleflash but not do the light spawning for JUST the rifle, only when it's silenced, and ONLY when it's being used by the player...but that would be a bit odd, since

A) the original rifle didn't have any muzzleflash at all, ever.
B) it's a gameplay change
C) hypercontextual code is just silly

And also, of course...*shifty eyes*...the rifle's modelled, animated, and in-game already. Without a muzzleflash. And there's no fucking way we're altering anything now.

Well... I suppose it isn't exactly "in-game" 'till I have it...

You suppose wrong. It's in-game, even if it's not your game in particular.

Well just say that is has some form of futuristic flash reduction system. It is both in the future and being a sniper you want to avoid detection so it works out perfectly. Hell you could even add something to the in game description to that effect.

Yes, let's say it reduces both the muzzle sound and the muzzle flash and let's call it a "sound supressor" - no actually, let's just say that most people call it a "silencer". And let's say it was invented around the beginning of the 20th century. In fact here's a Wikipedia article about it:

http://en.wikipedia.org/wiki/Suppressor