My 240Z with ZXT engine taching 6500 rpms with a .86 5th gear and 225/45 ZR16 rims/tires hits 138 mph with ease.
I am swithing the rear to a 3:70 LSD this weekend which will give me a top end of 145 mph.
I realize that calculated speed based on gear ratio's don't always tell the true story if you can't get your car does not have the torque/HP to overcome the air resistance. But in my case the engine so freely revved up to 6500 rpms in 5th with my 3:90 rear, that I can't imagine having any problems getting to the 145 mph mark.
KEY is Power/Weight: (2300 pound car with 280ZX Intercooled, Turbocharged, cold air induction, 3" free flow exhaust L28 engine)
The only thing I am not sure of is if I went with a 81-83 N/A 280ZX 5 speed with .74 5th gear, would I get to 160+ mph.
I think a G-nose, headlight covers, 18 pounds of boost, small lip spoiler in the rear and a comprehensive safety check would have to be in order to even come close.
Chas