When I accelerate hard in 2nd, 3rd, or 4th gear my RX8 is making a noise that sounds like metal grinding on metal coming from the engine area. Obviously this is a concern. It also results in lag and a loss of power. Car is 2003 with 60k on it. Has performed well until recently. Car is serviced regularly. Anyone any ideas what this might be before I head to mazda? Thanks in advance, Neil