Stephen got his off on the borders run in, oh say 0.5 second. Just find a hump backed bridge and watch the plastic fly. Or not.
Undertray off, zorst mounts off, 3 bolts, out. Sounds simple. Haynes 2 spanner job.
Reassembly is simply the reverse of removal.
Easy.
The undertray is alkward and fiddly (Not enough room for a socket screwdriver and very long bolts.)
The zorst nuts will be welded to the studs (Bolts on S2, or too much to ask?)
My mounts were bolted thru the boot floor with 3" long bolts. Took ages to undo.
Other than that nothing difficult on a new ish car.
Rich