Methods integrated tailcone muffler (ITM) is provided for minimizing noise generated while discharging pressurized air from one or more aircraft gas turbine engines. The ITM comprises a tail cone defining a conical backing cavity, the conical backing cavity having a large forward end and a narrow aft end and a porous exhaust liner with a first end and a second end, the first end coupled to an oil cooler eductor discharge plenum of a first gas turbine engine of the one or more gas turbine engines and a second end discharging to atmosphere via the narrow aft end of the conical backing cavity. The ITM further comprises a bleed air discharge conduit configured to discharge pressurized bleed air from the one or more gas turbine engines into the conical backing cavity and a firewall bulkhead defining the large forward end of the conical backing cavity, defining a first aperture passing the cylindrical porous exhaust liner and defining a second aperture passing the bleed air discharge conduit, the firewall bulkhead extending radially from both of the cylindrical porous exhaust liner and the bleed air discharge conduit.