in the FAQ on the homepage there should be something about a clip that holds the emergency brake line underneath the car. mine made noises over bumps also, i sprayed it down good (i believe on both sides of the car, this was like 2 years ago...) and haven't heard the noise since then. its a star shaped rubber grommet that holds the emergency brake line, you probably need to duck under the car just in front of the rear wheels to see it. try soaking it in some spray (wd-40, lithium grease, etc...) and see if that fixes it.
