[apbright]

Stock head, stock transmission, stock rear-end, no problem 50mph all day long, per all other posts here. My car has a 3.54:1 rear-end, a Mitchell 26% overdrive, and a 6:1 Snyder's head. I drive comfortably on California freeways at 65mph; I sometimes drive even faster than that, as I fear more someone crashing into me than the other way around. That said, much above 70mph even with balanced rims, new tires, and a tight front end typically feels unstable.