The GEN3 I put in my car recently came complete with a stuffed turbo. Sounded like a rock in a tin can. Use a long screwdriver or something, put one end near your ear and the other on a suspect part of the car. You should be able to hear where the noise is coming from. Be careful not to stick the screwdriver in the fanbelt. That will give you a good whack in the head. It could even be a loose exhaust manifold or heat shield. Have fun...