I bought a Tusk SS filter for my 450FX, and when I went to install it I noticed that the dimensions are slightly different than the OEM filter. It wouldn't concern me too much except that the overall length is a tad longer, and I'm worried about the extra pressure on the oil filter cover once the bolts are tightened. Without putting any pressure on the oil filter cover there is probably a 1/8" gap or so between it and the cases. The rubber gaskets on each end are also different than OEM (smaller diameter than the filter body). I contacted Rocky Mountain and they assured me everything would be fine, and I'm sure they are right but figured I'd ask before I shelf this one and buy something different.