My old 1989 BX DTR Turbo didn't have plastic coated pies but I have a friend who has a 1990 BX GTI 16v and his are plastic coated.
I may have varied slightly from model to model
Mark
Both my DTR Turbo and 16 valve are late 1989 (G reg) and neither had plastic coated pipes. the DTR does now at enormous expense and I expect I will be doing the 16 valve very shortly.
jeremy