Considering how long ago that was designed and engineered it is amazing how far beyond those guys where. Isn't there still many details of that plane still classified? I've hear mach 5+ and a ceiling somewhere in the stratosphere.
The pilot we talked to laughed about the rumors. The speed was unclassified at Mach 3.2 but they seldom ever flew it faster than 3.0. I think he said the ceiling was around 80,000 feet.
He was telling us that he went to a show where there was this guy who said he was a back seater and after listening to him talk for awhile he realized he was nothing but a fraud.
Like anything else where there is a lot of secrets, sometimes the truth isn't as much fun as the rumors are.