The Legacy S401 STI version was based on the BES Legacy Sedan RSK. With this model, STI aimed to provide exciting kinematic performance which would further expand the world of AWD sport driving, while offering a premium feel which satisfied the more mature driver’s expectations. In the engine, modifications in both intake and exhaust systems were made, and a special ECU was introduced. A manual balancing of the pistons, connecting rods and crankshaft was also performed. All these contributed to an increase in maximum output and a smooth engine rev-up. The drive system featured a front share track LSD and a 6-speed manual transmission. The steering was modified to a quick 15:1 gear ratio, the hydraulic pressure characteristics of the power assist revised, and the rigidity of the overall steering system increased. A reinforced coil spring, pillow ball bush rear suspension link and special front / rear stabilizers were combined, while the rigidity of the front cross member installation area, transmission installation area, engine mount, and bushes was also toughened. Brembo brakes and BBS aluminium wheels were also fitted. A 240 km/h speedometer, McIntosh audio system and other features made a vehicle which reflected a strong sense of STI’s professionalism everywhere, something which drivers could feel as soon as they sat behind the wheel.