Bought an XJ with CNG!?

I bought a 93 XJ last summer, started peaking around under the hood and discovered that it was at one point CNG. The key to switch back and forth is in the engine compartment. The fill valve is still there, although I haven't peaked around to find a tank. There is also some fuel management box - I believe BOSS is the name on it. All this is a surprise to me. It was clearly not professionally installed by the way the wiring harness has been spliced to hell to wire it all up. If anyone has any information on CNG conversions, I would love to know just what the hell I have wired up under my hood!

It stands for compressed natural gas. Probably was put back to stock before it was sold. I think you get a tax credit if you have it.

Just remove it all and send it to me