I’m not really sure if imports have any effect on the value of second hand UK models. Dealers put people off imports by insisting that the cars are completely different and that parts will cost a lot more. For most Jap cars this simply isn’t true.
With my last car, a Celica 190, I decide to go JDM because the suspension was better and the engine was tuned to run on higher octane fuel that they get in Japan. Didn’t want leather seats as the bucket in the JDM were better and the only other thing I can think of was the UK car had a headlamp adjustment knob. Great, I really needed that.
With the Z it’s a different story.
JDM has no headlamp washers (they can be annoying), different rear bumper as a result of license plate shape, no rear fog lamp, brembo’s are an option as are a few other parts, and the same applies with the interior.
Had a link that explained the options on the JDM Z but cant find it right now. Will keep looking.