I have a tbird v8, and the speedometer does indeed stop at 120, but they will definately go faster...much faster, the Supercoupes have 165 speedo's, it is actually a popular modification on birds like mine (switching the speedo's out)...trust me, when my built motor is done, I will fry some rice. (shooting for the mid 500 RWHP/600+TQ range)