I don't think that it is a problem with the car or gear manufacturers, mostly improper installs. It's kinda like plastic surgery. There are a couple of really good docs, then there are the guys that get their liscense out of the bottom of a cereal box. They can do the surgery, but it will more than likely come out screwed up. Pay a bit more and feel more reassured the first time. I had the guys at the first shop tell me that my gear housing was warped. If it was warped when you put the gears in, why didn't you stop and tell me at that point? Needless to say, it isn't warped and I now have zero whine. It cost $700 p&l, but it was worth it not to hear the whine anymore. Don't fear the gears, just the guy putting them in, IMO.
If you paid them with a credit card - protest the charge with the cc company. I use my AMEX card for everything I possibly can because you can file a protest online, they instantly credit your account while they research it. I have protested a dozen or so things and have never lost - goods and services...
2006 Redfire GT Vert Auto
, every factory option, 490rwhp JDM Saleen SC, One piece driveshaft, Steeda ultralight springs - rear adjustable UCA and LCAs, CHE relo brackets, Granelli front cross-member, Intrax sway bars, Tokico dampers, Hawk brake pads, Shelby Redline wheels and Nitto tires, GT500 exhaust, FRPP 3.73's, Pioneer AVIC-D3 navigation head unit, and Saleen HID headlights. See profile for appearance mods