A system including methods and apparatus for treatment of Obstructive Sleep Apnea Syndrome (OSAS), Chronic Obstructive Pulmonary Disorder (COPD) and other respiratory disorders. The system involves applying separate and independent gains to flow rates of pressurized gas delivered to a patient during inspiratory and expiratory phases of a respiratory cycle to deliver the pressurized gas in proportion to the respective gains during inspiration and expiration. A base pressure may be applied in addition to the gain-modified pressures and an elevated pressure profile may be employed to assist or control inspiration. The system may be fully automated responsive to feedback provided by a flow sensor that determines the estimated patient flow rate. A leak computer can be included to instantaneously calculate gas leakage from the system. The system may be utilized in connection with conventional continuous positive airway pressure (CPAP) or bi-level positive airway pressure (bi-level PAP) equipment to effect various beneficial respiratory disorder treatment applications.