did you actually read the comment you were replying to or watch the video

whitex said: ↑

modified bodywork isn't a small thing. the harnesses and sensors will be different, found in different places. if rear drive unit service requires removal of rear bumper and the bumper is custom, they won't have a step by step how to take it apart and put back together.

click to expand...

did you actually read the comment you were replying to or watch the video?
the bumper will remain totally stock, as will everything below the "waistline", i.e. rear light assemblies and down.
the only thing they will have to worry about in terms of electronics are the rear upper brake lights and the (new) rear window wiper.

these guys are no amateurs. they even have pilkington manufacturing bespoke rear and rear side as well as rear roof glass windows for them. the final product will have an almost as-from-the-factory look to it, no doubt about that.