Yeah I'll look into some koni's, I've heard that the rear bump stops are too long and that some off a fiat coupe may fit is that correct or something I've just made up?
The rear bump stops are long, giving the rear suspension little travel before bottoming out, the same problem the 500 Abarth has as they share a platform. This gets even worse by fitting lowered springs as the car continunally bottoms out on the bump stops. Fitting the Fiat Coupe bump stops improves things greatly as gives more suspension travel yet does what they are meant to do and prevent the springs becoming coil bound or the damper bring over compressed.
Rear dampers are known to blow causing rattling from the rear as not so obvious as not a lot of oil vapour on the damper body is present.
I have a Fiat Cinquecento with the Panda 1.4 16V engine and 6 speed gearbox with a Quaife LSD fitted, to get them made Quaife wanted an initial 20 ordered to justify set up costs etc, so I bought 3 as part of a group buy to help set it up, and consequently sold 2 to a guy in Germany who did rallies in his Panda 100HP, and know a couple of road going Panda/500 owners have fitted the diff as its brilliant. Pretty cheap at £600 and easy to fit, the crown wheel just unbolts for example.