i recently had all 4 shocks changed at my local specialist. they are japanes jobbies (gas ones) and are made by kayaba or KYB for short. I think they were £65 plus VAT for the front ones.
made a lot of difference, now more lurching through corners etc.
I found the grooved discs I had on make funny noises too. I have noticed that the initial bite isn't as good with the standard discs though. If I can't sell the grooved ones, they may go back on for track days !!!