the m111 engine is noisy. very noisy. and harsh. with that level of mileage it is completely normal for your vehicle to sound loud. some are louder than others. of course yours will probably be a little louder than one with half the mileage. if there aren't any drivability complaints, you are just opening the proverbial "can of worms" trying to seek out the cause. chalk it up to wear and tear.