I am adding side skirts a rear bumper and front bumper to my E36. What they mean by extending the side skirts is you will have to break it into pieces and add some sort of holder in the middle of the breaks. Some people use cardboard and then you need a lot of bondo and fiberglass, a ton of sanding to make it look good. If they only fit the base models (meaning Ford Probe…not GT) I would get a kit that says it will fit a GT, there may still be fittament issues but that is the case with most body kits, but at least it would be minimal. Me personally though I am taking mine into a professional paint and body place, because if not done correctly it can make the car really look bad.