I do believe it would, cat-back 120/180 being the same as long as both are same body type and model i.e. hatch or saloon, mk1 or mk2. One thing to bear in mind is the rear silencer joint, it'll need splitting to get it off the car.
The what joint? I havent had chance to have a look under the ZS yet. I managed to change the exhaust on my old R25 pretty easily but i dunno about this?!?!
I don't see why not - unless there is a difference in the exhaust diameters - let me just check in my service manual and I will let you know the diameter of the 180...
__________________ MGZS180+ Le Mans Green Hatch 2003
S/S Cat Back Cobra Sports Exhaust
ITG Induction