That doesn't sound that unusual to be honest. I imagine old, worn shocks become softer and 'baggier' over time, so it makes sense that the replacements feel 'tighter'. As long as it's not new fillings tme, then they sound like the ones to have. Other than that, it'll be a case of trawling the listings for someone who does Mondy ST200 shocks, now that it's been established that Mondy Mk2 shocks do fit, depending on what wheels you run.