Well I just finished reading up on the N52 oiling system and apparently it has a variable volume oil pump which means that it reduces volume with pressure and likely did that with the plugged oil filter! ;( Probably the noise I heard at the filter housing was not a by-pass valve but oil being forced around the ID oil filter gasket which I thought the Mehle had a better design with a rubber seal instead of the paper edge but probably made the problem worse! I guess at least the rubber gasket made a noise whereas the paper one probably would have allowed oil to flow by more easily but also not give any warning! Let that be a lesson!
So there is a bypass valve in the filter cap so that is probably what I was hearing, so maybe not so bad considering it was bypassing at idle when the pump is supposedly feeding more oil
