I've asked this questions among people at shows and thought I'd throw it around you people. I've hit 138 MPH in my 65 chevy supersport back in 1971 and I have the ticket to show for it. Must admit I was pissed at my girl and had to much to drink and really took it out on my car. Had a good friend(a state cop) who clocked me at 138 and didn't even try to catch me. Must admit it didn't take to long to get it to 120 but the front end really started getting squirrely after that to where the front actually started floating and thats when I backed off. Now I was running a 327 with dual 4 that was putting out 345HP but what was really amazing is that I was runniing 4:11 gears with a 4 speed M-21 and since I was trying to keep the car on the road, I never did get a look at the tack, but it had to be in the mid 7's and to this day I don't know why the engine didn't let go. Those 327 were great engines.