Plus one for short bump stops on the 100HP, but the OEM springs look like 1.2 springs cut short. Consequently, the ride is hard.
I fitted Fiat 500 rear springs from a 2015 car. They a lot softer and drop the ride height. I brought that back with a spring top rubber cush at both ends. Handily that also helps to protect the axle spring pan.
The cost was £20 all in, the ride is considerably better and height is unchanged. For additional cost, Bilstein or similar performance springs offer a rising rate so the initial bump is softer but you get less bottoming out on the bump stops.