I have a high pitch whine when I'm in 6th gear and applying throttle. It is more pronounced between 70-80mph and drops off below or above that speed. I was told by the seller that this was common on these transmissions at this mileage (270k). Is there any sort of mitigation I can do to reduce the noise? The car has been running Honda MTF and there are no obvious shifting problems. I've had the car for 20k miles.