A method of limiting an inflation system pressure for dilating a region of a patient's nasal sinus passageways. The method includes grasping an inflation device. The inflation device includes a syringe including a plunger slidably disposed within a barrel, a connector for fluidly connecting an outlet of the syringe with a surgical instrument balloon, and a mechanical pressure indicator associated with the syringe, the mechanical pressure indicator including a housing and an indicator body disposed within the housing. The method also includes delivering the surgical instrument balloon to a patient's paranasal sinus target area, operating the plunger within the barrel of the syringe to deliver pressurized fluid to the surgical instrument balloon, and transitioning the indicator body to extend outside of the housing when a predetermined inflation pressure of the surgical instrument balloon is reached.