This paper presents a critical study of the mechanical and electrical properties of the PHANToM haptic interface and improvements to overcome its limitations for applications requiring high-performance control. Target applications share the common requirements of low-noise/granularity/latency measurements, an accurate system model, high bandwidth, the need for an open architecture, and the ability to operate for long periods without interruption while exerting significant forces. To satisfy these requirements, the kinematics, dynamics, high-frequency dynamic response, and velocity estimation of the PHANToM system are studied. Furthermore, this paper presents the details of how the unknown subsystems of the stock PHANToM can be replaced with known, high-performance systems and how additional measurement electronics can be interfaced to compensate for some of the PHANToM's shortcomings. With these modifications, it is possible to increase the maximum achievable virtual wall stiffness by 35%, active viscous damping by 120%, and teleoperation loop gain by 50% over the original system. With the modified system, it is also possible to maintain higher forces for longer periods without causing motor overheating.