Lately I have been hearing what sounds like an exhaust leak or rattle on the passenger side at WOT. It is very loud, and sounds almost like someone hid a honda under the hood. I am planning on headers in the next month if they get here, but was wondering if this has happened to anyone else before. I do not have any CELs from the O2 sensor, and the sound is gone under 3000 RPM. I don't know if it is a blown exhaust manifold gasket (which is what I think) or perhaps something more sinister. Should I schedule a trip to the stealership, or go for the header install and hope it isnt something on the cylinder head?