what?  haha no, there are no ill effects to the motor from installing motor mounts. they're not solid mounts, they still give quite a bit, particularly the inserts. If it's really bad your mount may be broken. They are made of very bad material and if broken could allow the motor to twist around and potentially hit the firewall. either jack up the car or pull one tire up on the curb and slide under there and check it out.fliphandywork said:I have a set of Prothane front mounts but I heard that if I install them without getting the idle raised it will knock due to their stiffness. Is this true?