I had noise issues with the trailing arm bushes on my S3 which took a little while to isolate. I replaced them with OEM parts at first, but these very soon proved to be short lived and the problem returned all too quickly. I then replaced these with Powerflex bushes and finally the problem has been completely rectified. Good news is that the Powerflex bushes are super easy to fit as they do not require to be pressed in. That said, however, the OEM bushes need to be pressed out first which will entail typically Garage equipment. I prefer to remove the trailing arms on Quattro models to fit new bushes and this is can be a little involved for the DIY mechanic. Lastly, ideally the car will require wheel alignment, post works. So it might be a garage job, unless you feel confident to proceed.