Hmmm... Unless you're an experienced mechanic, you'd just be better off turning in at a dealer. Is your car still in warranty? Be sure not to void it - though I see now it has 122kmiles, so probably not covered anymore. Just don't forget to let the car warm up for a while before starting to rev it maddly, it certainly won't do any good.
Could the noise be a stuck injector? Or the pistons slammering the engine's head? Once I ad a problem with a secondary belt (the aircon/power steering one), and, due to forcing the car to startup a number of times, the timing belt skipped 2 teeth. The noise was loud and clear, like an old diesel hammer, and power was gone. Luckily, no harm was done to cylinder heads, pistons, valves or camshafts, but it was close. And the noise has never been quite the same since.