Bounces just right when pushing down on boot.. Normal driving feels ok too apart from when going over bumps as that's when I hear the " banging" noise.. Just rang local Vauxhall dealers and they have a pair in.. £168... Do I need them ?
Upto you... How old/mileage?
Replacing with standard will require a spring change if it has Elite springs fitted.
IME the mounting kit will now be part of the strut if all original. But if shocks are newish you should be able to undo the top mount and compress it to investigate the state of it. If they come apart, including the metal bush and washer, then simply replace the mounting kit using the parts listed elsewhere.
If they don't, or the shocks are getting on a bit, then replace the lot for the sake of a job done right
Second hand self-levelling shocks have some value if they basically work and are leak free, so you could potentially recoup the cost of the fittings