I topped out an 89 XR7 5-speed many years ago. The speedo in the car only went to 120, so I watched the tach until it stopped climbing, at just under 4100rpms in 5th. When I got home I calculated it out based on the tire size and gear ratio, and it came out to 157mph. The only performance mods to that car were an aftermarket exhaust with no cats and a mid-mounted flowmaster, and a ported early style blower with a 10% OD.