Both internal and external hydraulic clutch release systems can have major failures if over-driven. Tilton's instructions are excellent and make this point very clearly. But the same idea is true of all types and brands. For both my Coupe and now the Mk5, with Tilton HRB's, I didn't install clutch stops. Heresy you say? In both cases, with the clutch pedal hard against the back wall of the footbox, I'm not exceeding the throw and the clutch is fully released. So a clutch stop wouldn't add anything. This is the result of using a 13/16" MC (Tilton recommendation) and where the Wilwood pedal is located. YMMV