The standard loadout for the AH-1S was up to eight TOW launchers and two 2.75in 19 shot FFAR pods, which is what comes in the kit. To the best of my knowledge, there are no aftermarket sets available for that Revell kit.
What you could do if you're looking for something different is unload the TOW launchers, and replace the detail with bits of styrene and fine wire. For the FFAR pods, drill out the launch tubes slightly to give the appearance of an unloaded pod. Or, see if you get another set of the FFAR pods and arm your Cobra in a "Heavy Hog" configuration (for a total of four 2.75in FFAR pods).
Cheers,