Ok, I'll start this post by saying that 25k miles ago I had the subframe bushes replaced with Powerflex ones (or rather, the previous owner did, and I've got the paperwork to prove it). When going over rough ground/bumps, I get a knocking/creaking sound from the rear right. I've removed all items from the boot including the spare wheel, so I can rule that out. Normally I realise this would be indicative of a £200 job to get the subframe bushes replaced, but given that they were done so recently, is there anything else (hopefully cheaper!) that could be the culprit? The other part of the question is - whatever the potential cause, is this likely to make the car in any way unsafe to drive? Cheers.