The fastest I have been is 135mph in a stock Mazda MX-6 turbo and I let off when I felt the front end start lifting off the ground. This is scary, the car had more in her but i was not going to test it. Picture is what the car looked like but this is not mine.
135 as a passenger up and down hills, it was crazy cuz I can remember flying by a 35 mph sign then looking over and seeing us 100 over, its one hell of a rush but Im not sure I would do it again, it was in my friends Mustang, maybe a 98 GT, im not sure, its an all black beast, most I ever got in my 78 grand prix was 215, guessing cuz the speedometer doesnt go that far, and my 79 cadi eldorado has plenty of potential w/ the 350 v8 and high rize eddle broc intake and 4 barrel carb / no the stock fuel injector kit
I hit 135 in a 74 Nova. I don't know all the specs but it had headers, side pipes, and a shift kit. This beast would squeal the tires at 90. Not my car but I spent many hours riding in it. I usually got to drive when my friend got too drunk.
I had an 82 Mustang that I was clocked in doing 125 in a 25 zone. The cop was laughing at me cause I lost him till he saw my car parked in my parents drive with the engine smoking. He only wrote me up for 35 in a 25 and said that I needed to slow it down.
The fastest I've been was 142 in my grandfather's 94 Corvette. I let out with about 1/4 pedal left. Once you're going that fast on the Interstate it basically feels like the car is floating and very unstable... not really a fun feeling.