I have a few SC-811s and HU-xxx but i didn't much like the the HU-xxx with the built in CD player. I did however find the issue with my SC-901! From looking online it seems to be a common problem with the 900/901 units and I found the culprit, on the right side of the unit (front facing you) theres ...

Back to the original question. I bought a set of Rensi rubber floor mats years ago for my 98' V70XC, which is the same as for an 850. The fit was terrible, they looked like they were a size too small. To make matters worse, they had nothing to hold them in place and they were sliding around. I think...