Does anyone else have a noise from the pass side rear seat area that is speed sensitive only? It sounds like high pressure liquid going thru a metal tube. A friend of mine had an M3 that had the same noise and no one ever found out what it was. It is definitely speed sensitive only, because when I put the car in neutral and coast it is constant with speed, and when I slow down it lowers in intensity. I thought it was the fuel pump or fuel rail but that would not be speed sensitive but throttle sensitive. Any suggestions?