Strippersteel, Isaw your question adn here's my attempt at an answer. It seems that at this time there is no strait-forward, drop-in airsoft replacement unit or kit to make HL airsoft tanks IRbattle capable. First, you need the hardware to shoot and recieve IR signals; that's the battle unit everyone is talking about, and they've gotten to the point of being almost plug-and-play. HOWEVER, you also need a muzzle-flash of some kind, and this gets tricky. Some of the battle units will take care of this for you, like the DBC and the SLU (and the IBU, IIRC). However, these do NOT allow for the "high tension flasher" unit from HL to function, as you are bypassing this function on the RX-18. That last bit was probably gibberish, but take my word it doesn't work without some monkeying around. So basically, the muzzle flash is possibly taken care of by your battle unit (most likely, but make sure when you're reading about the unit in question). The worst part is that you'll likely want a recoiling action barrel as well, and this gets REALLY difficult. You see, the the HL Airsoft unit is completely different than the HL recoil unit, which is cheap but nasty in it's way (but is low cost, and works). The Airsoft is triggered by a completely different circuit that isn't exactly used by the IRunits, and many of the aftermarket HL battle systems co-opt this function and render it unavailable to make the HL recoil unit work. For instance, you plug the DBC into the jack where you'd need to plug in the HL recoil unit (and several other functions, but lets talk about those another time). The DBC then supplies a SERVO recoil controll function, but as far as Iknow (though I'm not sure) doesn't just give you a blip of pure voltage like you'd need to get a recoil unit going. So more monkeying, a bit of soldering and a LOTof swearing later and MAYBE you have something that works...it's a headache. It CAN be done, and I'd personally love to know more about it, but you're going to have to learn alot from haunting forums, ask a bunch of questions, probably pester YHR, and build some things from scratch. However, once you're done, you'll have a sweet tank and the ability to do ANYTHING you want with it. So don't get discouraged by my doom and gloom; just know it's a bit of a learning curve.

EDIT: Ijust remembered; the IBU has a neat little feature that lets you switch from servo-recoil to HL/ Tamiya recoil operation at the flick of a DIPswitch. Nice, eh? that'd save you a bunch of sweat, Strip. Just don't load so much paint onto your barrel that it gets stuck...>.<