For pure speed, they notched 1,852 mph. They could climb to 98,425 feet in four minutes and 3.86 seconds and ultimately reached an absolute altitude record of 123,520 feet.
That top speed would need a complete overhaul, if not replacement of the turbines afterwards. The somehow derivative (only by the looks, innards not so much) https://en.wikipedia.org/wiki/Mikoyan_MiG-31 can do that on a more regular basis. (Allegedly)
Back to the OP topic, the Arrow's thrust to weight ratio meant that it was theoretically the first aircraft capable of accelerating directly upwards in an arc immediately after reaching the end of the runway. Hot stuff.
For pure speed, they notched 1,852 mph. They could climb to 98,425 feet in four minutes and 3.86 seconds and ultimately reached an absolute altitude record of 123,520 feet.
https://www.historynet.com/mig-25/