Don’t know how much trouble it is to get existing injectors to work OK with the natural gas. A gas will pass more easily through them than a liquid. They are also designed to contain higher pressures than carburetor fuel feed systems are. But the central computer would need to be changed to one that recognizes the new fuel and its characteristics, and that’s well over $200 right there.
“But the central computer would need to be changed to one that recognizes the new fuel and its characteristics, and that’s well over $200 right there.”
I’d suspect that could be accomplished with an EPROM (eg; firmware) change which wouldn’t be the biggest of deals, though these units aren’t exactly made to be screwed around with. I have no idea whether the NG is fed to the fuel injection manifold as a liquid or a gas, and if a liquid, whether some evaporator in the form of a small external tank is req’d. None of the many steps req’d are particularly difficult in and of themselves, but the totality is a lot of individual steps. And each of them is, I’m sure, quite well known, but I still believe that the entire process of taking a car built for gasoline and converting it for NG from beginning to end is non-trivial.