Mike, GM says the Z06 exhaust outflows the C5 exhaust by quite a bit. I don't remember the specifics, but it might be like 25%. I have a Z06 exhaust that I removed from my car with under 100 miles on it. I wouldn't let it go for less than $900.
From GM preliminary info in 2000 RE the titanium exhaust for the Z06:
"To further maximize the breathing capabilities of the LS6, and reduce vehicle mass significantly a new titanium exhaust system was developed for the Z06. This marks the first-ever use of titanium in the exhaust system of a mass-production vehicle. The titanium portion of the Z06's exhaust system starts just forward of the rear axle then goes over the top of the axle to the muffler. The entire muffler, all of its internal parts and exterior skin, the outlet pipes, including the exhaust tips, are constructed of titanium.
The Z06 muffler is a completely-new design, featuring larger diameter louver tubes inside the mufflers to reduce back pressure and provide less restriction for the exhaust gases flowing through the system. The exhaust tips are different too, with four 3.5-inch diameter tips to visually set the Z06 apart from the standard Corvette.
Titanium offers a lower density than steel, and higher strength than either magnesium or aluminum at all temperatures. It reduces the Z06's weight by 17.6 pounds - a whopping 50 percent reduction over the weight of the stainless steel exhaust system used on the Corvette coupe and convertible. In addition to easing exhaust gas restrictions, reducing mass and looking distinctive, this exhaust system sounds more "aggressive" than that of the standard Corvette. Considerable time and effort went into the design and tuning of the mufflers to ensure an exhaust note that would be unique to the Z06. "