A gas turbine engine (10;10';110;110';210;210';410;410';510;510';610;610'), comprising: a low pressure compressor section in fluid communication with an air inlet and drivingly engaged by a low pressure turbine section, the low pressure compressor section having low pressure compressor stages (26A, 26B) spaced apart along an axis of rotation of the low pressure compressor section, and the low pressure compressor section having a fluid conduit extending between the air inlet and the low pressure compression stages (26A, 26B), the fluid conduit (27;227) having at least one flow diverter (28A, 28B) displaceable between a first position and a second position to modulate air flow through the low pressure compressor stages (26A, 26B), the fluid conduit (27;227) including a first fluid conduit segment (27A, 27B;227A, 227B) extending between the air inlet and one of the low pressure compression stages (26A, 26B), and a second fluid conduit segment (27A, 27B;227A, 227B) extending between the air inlet and another one of the low pressure compression stages (26A, 26B), the first and second fluid conduit segments (27A, 27B;227A, 227B) meeting at a fluid conduit junction (27C;227C), the at least one flow diverter (28A, 28B) positioned about the fluid conduit junction (27C;227C) and displaceable between the first position to direct air to both the first and second fluid conduit segments (27A, 27B;227A, 227B), and the second position closing the fluid conduit junction (27C;227C) to direct air only to the first fluid conduit segment (27A, 27B;227A, 227B); a high pressure compressor section in fluid communication with the low pressure compressor stages (26A, 26B) to receive pressurized air therefrom and drivingly engaged by a high pressure turbine section; and an output drive shaft drivingly engaged by the low pressure turbine section. a low pressure compressor section in fluid communication with an air inlet and drivingly engaged by a low pressure turbine section, the low pressure compressor section having low pressure compressor stages (26A, 26B) spaced apart along an axis of rotation of the low pressure compressor section, and the low pressure compressor section having a fluid conduit extending between the air inlet and the low pressure compression stages (26A, 26B), the fluid conduit (27;227) having at least one flow diverter (28A, 28B) displaceable between a first position and a second position to modulate air flow through the low pressure compressor stages (26A, 26B), the fluid conduit (27;227) including a first fluid conduit segment (27A, 27B;227A, 227B) extending between the air inlet and one of the low pressure compression stages (26A, 26B), and a second fluid conduit segment (27A, 27B;227A, 227B) extending between the air inlet and another one of the low pressure compression stages (26A, 26B), the first and second fluid conduit segments (27A, 27B;227A, 227B) meeting at a fluid conduit junction (27C;227C), the at least one flow diverter (28A, 28B) positioned about the fluid conduit junction (27C;227C) and displaceable between the first position to direct air to both the first and second fluid conduit segments (27A, 27B;227A, 227B), and the second position closing the fluid conduit junction (27C;227C) to direct air only to the first fluid conduit segment (27A, 27B;227A, 227B); a high pressure compressor section in fluid communication with the low pressure compressor stages (26A, 26B) to receive pressurized air therefrom and drivingly engaged by a high pressure turbine section; and an output drive shaft drivingly engaged by the low pressure turbine section.