Ditto!
Straight-cut gears may be louder than normal gears in real life, but they never drown out the engine. I own a car with a little 1.4L engine and a small exhaust. I can say from experience, if your gears are louder than your engine, your gears are broken. Get them fixed before your transmission consumes itself and leaves you stranded.
I was baffled when I was driving a NASCAR racer for the first time in GT5. The gears drown out the engine in NASCAR? Not ****ing likely. The exhaust on those cars is designed to produce sound frequencies that stimulate the brain toward excitement. In other words, they're designed to sound cool. They're not loud just to be loud, but they're designed to be heard. What kind of revenue would NASCAR have if the cars went by the stands and the spectators just heard an ear-splitting gear whine? NASCAR would go broke pretty quickly.
I've also been around real musclecars enough to have heard a Muncie M-22 "Rock Crusher" transmission. They're not straight-cut gears, but it has the gears cut at a shallower angle than most transmissions. It's one of the loudest transmissions ever, and I'm sure it's the loudest mass-produced for American cars. You can hear it if the car is cruising along at low RPM. If the driver gets on the gas, any V8 will drown out the transmission noise. The particular case I heard was a dead-stock Oldsmobile with a 2" peashooter exhaust. If the engine was revving, you could barely hear the transmission.
If PD wants to call their game "The Real Driving Simulator", they need to turn down the transmission noise to about a quarter of what it is now. Unless this kind of thing gets fixed, my chances of buying GT6 are pretty slim.