rumbling sound right front inside cabin

After a long trip, the car developed a loud rumbling noise coming from the right side of the car(sounds like it is a loud exhaust and vibration). Sounds louder from inside the car. And the noise goes away from time to time. I checked the exhaust and it looks good. It may be coming from the engine and I'm afraid it may be the turbo. I also heard something about chain tensioners, compressor and alternator. Can't seem to pin it down b/c it is heard loudest inside the car. When accelerating, it is loudest, but I depress the clutch and it goes away, makiing me think it is not in the suspension or bearings. I read another post on fixya.com where another person has the exact same problem. She had her alternator and chain tensioner replaced and they came back w/ compressor. Still has noise. Any idead would be greatly appreciated. 2004 9-3 linear. 56k.