I'm getting a noise from my FRPP Aluminum DS whenever im am driving at 55~60 mph. Theres no vibration and it does not sound like it is rubbing anything. The only way I can describe the noise is if you have ever held one of those tuning forks up to your ear, thats what it sounds like. I checked under the car and there was no signs of it rubbing on anything. Is this noise normal? What should I be looking for?