springs or shocks

Gentlemen, Took my E Class Estate four-up on a run yesterday and couldn't help but thinking that the ride had got firmer since I bought it 3 years ago. 149,000 miles and by the look of the full MB history it's never had any suspension needed. Tyres are all good and balanced. Should I...

As above really guys, only height adjustable kit I can find for the clk is the KW V2 kit and quite frankly I'm not up for dropping 1500 on em! I've seen cheaper d2 kits etc for the w202 and I'm wondering if they'll fit? Alternatively are just the springs interchangeable incase I decide to...