I did some work on a UR Quattro recently, nice car, but this one had been modified, and then modified again, and was a bit of a mess under the bonnet, alledgedly made huge BHP but as is so often the case all the bodged wiring was causing all sorts of problems.
Boss had an S2 (20v UR engine), then an RS4 (heavily tuned V6 version) which buckled 2 or 3 sets of wheels, then an RS6 which again was heavily tuned, this one destroyed its gearbox and had to have all the mods removed so he could claim a new box on the warranty, he then went all Hairdresser and bought a Maserati Quattroporte.