Hi, Al. I've been running a Flowmaster 50 series, 2" inlet and outlet, on my Nissan truck with Pacesetter headers and it's so quiet I can hardly hear the exhaust note unless I have a window down. It sounds like you might have some exhaust vibration being transmitted into the car body or frame. Is your whole exhaust system isolated from the body or chassis? If there's a solid connection anywhere (i.e.,exhaust pipe welded to any part of the frame or floor pan), it transmits sound waves directly into the car interior and will darn near drive you nuts. Make sure that all of your exhaust system is isolated with rubber hangers and that there's no metat to metal contact anywhere. An H pipe certainly won't hurt, and might even give you a smidge more torque.
