The newer 8 cylinder cars (355 and 360) have a solenoid that opens up at around 5000rpm, it allows the exhaust to flow easier. At least on the stock exhausts they do, aftermarkets don't. Ferrari claims this is to help with low end torque, although there maybe some validity to that (very very little), it's mostly to deal with noise regulations and emissions. Kind of a tangent, but for those familiar with modern powerboats, most of the same type of exhaust valve except that are operated with a switch on the console whereas the ferrari does it automatically.