[Herp Derp Version]
A gun that could turn their enemies' engine off.
Simple, we use a Sniper, add the anti-lag system for it. Sell it at Drunk Gunz for 100k per ammo.
It's very useful against Hydras, Hunters and NRG (so this is basically balanced. Not in favor of any class)
[Detailed Version]
We add a very advanced Sniper Rifle (like the Cop's Desert Eagle/Tazer)
With the Anti-Lag script that is possible, It wouldn't be impossible to take down fast annoying vehicles!
When hitted, Your Engine will fail to start for 20 seconds.
This suggestion benefits both side of the game. Either disabling annoying Military Aircraft or fast vehicles.
To get the weapon, Drunk Gunz would be selling it 100k per bullet. And of course, rules should be set up to avoid using this.