I own a 1999 Audi A4 quattro 1.8turbo. I think the turbo is going out and the car rattles in D and R but not in P and N. I am also debating on replacing the turbo or not but I do not know if it is completely shot. Also considering an apr stage 1 chip and I have been told that it would be best to replace the whole exhaust system. NEED ADVICE! thanks, I am a rookie