The key elements of the Works MCS
conversion was the engine modifications to produce the extra BHP. Other performance modifications and accessories were available form John Cooper Garages such as the Aero kit, grill, seats, steering wheel, up-rated brakes, strut braces, suspension, exhaust system, engine airbox etc.
You may find real Works cars that have no external badges and the standard exhaust so apart from the engine cover and Works engine plate they don't look any different to a standard R53 MCS
I think its fair to say that all the JCW
mods and accessories were very expensive so a lot of the original cars were quite spartan with there specification.
You will also come across ordinary Coopers and Cooper S where any of the non-engine accessories have been fitted (including the exhaust) and they do look like a proper Works, but they don't go like a Works!
One of my neighbours has what appears to be a Works MCS
with aerokit, grill (but no Works Badges)......when I got chatting to them about it, turns out to be a standard Cooper that has had all the body works mods of a Works Cooper S installed including an S bonnet with air scoop! They bought it for their daughter to get cheaper insurance!
As I have said before, you really need to have a very detailed inspection of a potential purchase and do some investigation with BMW and/or any previous service garages.
My own car is an original Sept 2003 BMW-fitted Works conversion (210bhp)
which was subsequently fitted with the 225bhp engine conversion by John Cooper Garages.
It has the full Works exhaust and sports CAT and Cooper Challange Cup brakes up-grade (6 pot front calipers).
The engine plate number does not correspond to the Works Certificate issued by the original BMW dealer, because when JCG's fitted the motorsport spec, engine modifications they installed a new engine plate with the number of this conversion on it. Luckily when I bought it, I was able to speak to the specialist garage that looked after the car and they were able to tell me the full specification of the engine and a bit about the history of the vehicle.