I recently had a local performance shop install 4.10 gears & a master bearing kit on my 2001 Mustang GT auto. There is a noticable "whoob whoob whoob" noise that can be heard upon decelleration only. No noise is present when accellerating or cruising. What's interesting is it's really pronounced after tapping the brakes when coasting from around 50 to 40 mph. I figure that tapping the brakes eliminates stress on the drivetrain which is why the noise is so obvious. It sounds like a bearing to me. The shop told me that the 4.10 gears are known to accentuate drivetrain noises that aren't noticable with the stock gears. They said an aluminum driveshaft might cure the noise. I don't buy it. Any ideas or suggestions? Thanks !