I just sold my 84 S12 turbo. US spec models did NOT have a CA18DET. They had a CA18ET, CA20E, or VG30E. Only the 84-86 SE's (hatches) were turbocharged, after that they had the VG under the hood. I'd stay away if it's a coupe unless it's got a swapped motor or something.

I don't believe we, in the US, had the FJ option. Pretty sure that was a Euro/JDM thing. As usual.

But yeah, club-s12.org for all your info.

EDIT: Just noticed you said it has a CA20E. I wouldn't boost it. I'd just swap in something else, IMO.