For those that have swapped rear springs may have noticed the worn stock rubber isolators. These are more durable replacements that may also help with creaks and squeaks.
https://www.powerflex.co.uk/road-series/product-details/Rear+Spring+Upper+Isolator+/12752.html
https://www.powerflex.co.uk/road-series/product-details/Rear+Spring+Upper+Isolator+/12752.html