A method of upgrading an ebullated bed hydroprocessing system that includes one or more ebullated bed reactors to increase rate of production of converted products from heavy oil, comprising: initially operating an ebullated bed reactor using a heterogeneous catalyst to hydroprocess heavy oil at initial conditions, including an initial reactor severity and an initial rate of production of converted products, wherein the initial reactor severity includes an initial operating temperature of the ebullated bed reactor, an initial conversion of heavy oil, and an initial throughput of heavy oil, wherein throughput of heavy oil is the quantity of feed material introduced into the ebullated bed reactor as a function of time; thereafter upgrading the ebullated bed reactor to operate using a dual catalyst system comprised of dispersed metal sulfide catalyst particles and heterogeneous catalyst; and operating the upgraded ebullated bed reactor using the dual catalyst system to hydroprocess heavy oil at higher reactor severity and increased rate of production of converted products than when operating the ebullated bed reactor at the initial conditions, wherein the higher reactor severity is characterized by: increasing the throughput of heavy oil and increasing the operating temperature of the ebullated bed reactor while maintaining or increasing the conversion of heavy oil than when operating the ebullated bed reactor at the initial conditions; increasing the conversion of heavy oil and increasing the operating temperature of the ebullated bed reactor while maintaining or increasing the throughput of heavy oil than when operating the ebullated bed reactor at the initial conditions; or increasing the conversion of heavy oil, increasing the throughput of heavy oil, and increasing the operating temperature of the ebullated bed reactor than when operating the ebullated bed reactor at the initial conditions. initially operating an ebullated bed reactor using a heterogeneous catalyst to hydroprocess heavy oil at initial conditions, including an initial reactor severity and an initial rate of production of converted products, wherein the initial reactor severity includes an initial operating temperature of the ebullated bed reactor, an initial conversion of heavy oil, and an initial throughput of heavy oil, wherein throughput of heavy oil is the quantity of feed material introduced into the ebullated bed reactor as a function of time; thereafter upgrading the ebullated bed reactor to operate using a dual catalyst system comprised of dispersed metal sulfide catalyst particles and heterogeneous catalyst; and operating the upgraded ebullated bed reactor using the dual catalyst system to hydroprocess heavy oil at higher reactor severity and increased rate of production of converted products than when operating the ebullated bed reactor at the initial conditions, wherein the higher reactor severity is characterized by: increasing the throughput of heavy oil and increasing the operating temperature of the ebullated bed reactor while maintaining or increasing the conversion of heavy oil than when operating the ebullated bed reactor at the initial conditions; increasing the conversion of heavy oil and increasing the operating temperature of the ebullated bed reactor while maintaining or increasing the throughput of heavy oil than when operating the ebullated bed reactor at the initial conditions; or increasing the conversion of heavy oil, increasing the throughput of heavy oil, and increasing the operating temperature of the ebullated bed reactor than when operating the ebullated bed reactor at the initial conditions. increasing the throughput of heavy oil and increasing the operating temperature of the ebullated bed reactor while maintaining or increasing the conversion of heavy oil than when operating the ebullated bed reactor at the initial conditions; increasing the conversion of heavy oil and increasing the operating temperature of the ebullated bed reactor while maintaining or increasing the throughput of heavy oil than when operating the ebullated bed reactor at the initial conditions; or increasing the conversion of heavy oil, increasing the throughput of heavy oil, and increasing the operating temperature of the ebullated bed reactor than when operating the ebullated bed reactor at the initial conditions.