this may be an ignorant comment because I am not sure it is viable but I'll give it anyway. I have a pair of sound canceling earphones that I use on airplane flights, and it does an amazing job of eliminating the droning sound from aircraft engines. I wonder if anyone makes some version of sound canceling for automotive use becuase I have tried my earphones while driving in my eclipse with a loud apexi N1 exhaust and it reduces the sound level immensly. Obviously you cannot drive around with them on for safety reasons, but I wonder if anyone makes a car version.