Before you spend the cash,
Congratulations on a great rifle!
Are you SURE that you want / need a flash suppressor? From the picture and the description, I believe that I may have the same model. With the ammo I use, I haven't noticed much need for one yet (XM-193, American Eagle 55g FMJ, Corbon 53g DPX).
By no means am I saying that the suppressor is bad. For myself, there are other ways in which I would spend the money (I just want one CHEAP hobby!).
One area I do recommend spending a bit on is the grip. Its a very subjective thing, but I'm very happy with the change.
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One more parting thought: It looks like you have the h-Bar (heavy Barrel) configuration. If this is to be used for home/self defense, you might consider a new upper with a thinner barrel (which usually comes with a flash suppressor).
Try this sometime; with the rifle UNLOADED and pointed in a safe direction, hold an imaginary bad guy at gun point. That heavy barrel gets very heavy very quickly, realize it might be a long time before the police arrive and make the arrest. Just a though/observation.