Surface pressure-sensors have been used to measure the second-mode boundary layer instability on a 7° half-angle sharp cone at zero angle of attack in the quiet Mach-6 wind tunnel at Purdue and in the conventional Mach-6 wind tunnel in Braunschweig. The measurements were made using a stream-wise array of high-frequency sensors. They show the second-mode waves in quiet and noisy flow at different unit Reynolds numbers. The quiet flow data is compared to results in noisy flow. The signal quality allows for the calculation of amplification rates, which are compared to the results of linear stability computations.