The thing that everyone forgets is there is as much intake noise as exhaust. In a Spyder, the intakes are about a foot from your ears. Unless you address that, ALL exhausts are too loud.
I built and installed a short extension on my Vintage Motorcars exhaust. It's a simple 3" ID extension with a clamp(a slot, a bolt, and a tube welded on). Inside is a Vortex cone insert, which takes the edge off the exhaust without adding any restriction. These are used in V8 cars with open headers to drop a few decibels to meet track sound requirements. The extension also keeps a lot of the soot off the paint in the license plate area.