I am just about to have the rear radius arms re-done on my car and ws thinking of having new shocks at the same time. Not sure if i should go for a set of bilsteins or just replace te standard ones. I will be keeping the standard springs and don't want the ride quality to get any harder. Any advise?

Go for the Billys, those dampers are designed to be used with standard springs.
Out of all the suspension I have tested on the coupe, bilstein and standard springs was by far the best quality ride.

I'm running bilstein b6 + eibach springs and they are great. the improvements are enormous and the ride quality is as good (or as bad ) as on the original set up