Ok heres the story. O dark 30 on the way to work I go to pass this Honda looking car (it was dark). Iwas doing about 85mph and I went to pass this car as I went faster he went faster we get up to what my speedo says is between 115 & 120mph and he backoff and looked to me like he pulled onto the shoulder, I was to far up the road to see for sure (again it was dark). Anyway hers my question How accurate are speedos up top. Here more info on my run. I was doing between 115 & 120mph the tach was just over 5500rpm. It's a unmodified 75. Tire size is 225-60-14. One more thing It's a 81zx 5spd but I lost 5th gear about 2 weeks ago so I was running in 4th gear. Stock diff in it. Speedo cog was changed out to match stock diff. I find it hard to belive I was doing that speed in 4th. But it was smooth.