Richmond hum?

Hey guys, I had my Richmond 3.73's put in today. After a couple minutes of cruising with my mechanic, they started to hum. We took the rear apart again, shimmed it more, and it cut down a lot of the hum. My cousin, who owns the garage I had the work done at, talked to one of his friends who owns one of the most reputable rear-end places in NJ. They've been installing rears for more than 20 years, and said that no matter what, for some reason or another, Richmond's always hum in our 7.5" 10 bolts. Any truth to this?

The current rumor is that Richmond gears are noisier than others, particularly GM gears.
The question then becomes subjective. How much noise is to much?

Mines not bad. Can't hear it on the highway over the exhaust.

That sounds like a pretty accurate statement. All the Richmonds I have ever heard whine like crazy.