What the Black Manta's statistics are thought to be:

 Little is known about the Black Manta, and there have been fewer sightings than of it than the Aurora. There is also dispute as to what the contractor is, although everyone knows that it is Northrop (If the Black Manta actually exists).

The TR-3A Black Manta was designed for stealth. It is a flying wing, and a cross between the F-117A and B-2. Observers say that it has rounded tips, but there are also reports of a craft with more sawteeth across the trailing edge, called the "Artichoke". The TR-3A is said to be much quieter than the stealth fighter F-117A. It is supposed to be a follow-up on the F-117A. Although some people say that it could be used in the Gulf War, in operation "Team Stealth", that would mean that the F-117A and the TR-3A were developed at roughly the same time (+/-10 years), and that would be almost impossible. The TR-3A is much more advanced than the F-117A, and it takes many years to produce such a big improvement. Still, the TR-3A is reported to be flying with KC-135 tankers, F-117s and T-38s, and is thought to have a capability to collect and transmit information back to F-117s, which was supposedly it's role in the Gulf War.

Although I believe that the Aurora is a myth (there might be an aircraft just slightly faster than a SR-71), because the government is in the process of researching Mach 3.5+ flight as we speak, I think that the Black Manta exists. It is really not that hard to produce a really stealthy aircraft, much harder than producing an aircraft that goes Mach 6-20.