There's anadditional noise encapsulation panel underneath the car, and it has an insulative blanket affixed to it; also, the interior carpet is D-specific, I believe with more sound deadening material. Also, there are a lot of small insulated pieces throughout the nose of the car-the motor's sealed pretty darn tight.
"If everything seems under control, you're simply not going fast enough" --Mario Andretti
1995 E500 street car
1986 Porsche 944 Turbo S track car