Terrible rattling/clatter sound

[jordan986]

Just started happening in the last month it is comming from the driver side rear I can hear it with the window up but it dosent sound too bad... when I put the window down it sounds terrible like a metalic valve clatter sound fresh oil change did nothing to improve it. This is a consistant noise at any speed in any gear however not at idle. I am really hoping it is not the valves, It is not suspension related possibly exhaust??
any ideas or experiences with this whould be greatly appreciated thanks
Jordan

also hot or cold has no effect on the noise

Could be the cats. Or the heat shields on the cats.

[jordan986]

I've already had the heat shield issue this one seems different Its a fairly new $2000 exhaust setup the cats shouldnt be gone yet (I drive very spirited however I will look into that) thanks

[Dohertycm]

My mechanic told me that the spark plugs also cause a knocking type noise in the boxster when they come loose. They require a higher than normal torque...which I cant remember. But check those.

Chris