Header construction and techniques are disclosed that utilize header layers that provide support for electrical interconnections. A sensor header assembly includes: an upper header layer having upper through holes arranged in a first configuration; a lower header layer having lower through holes arranged in a second configuration axially offset relative to the first configuration; depressions extending from the lower header layer top surface and partially through the lower header layer, each depression defining a footprint corresponding to the first configuration of the corresponding upper through holes of the upper header layer; upper header pins extending through the corresponding upper through holes and at least partially into the corresponding lower level depressions; and lower header pins extending through the corresponding lower through holes and in electrical communication with the corresponding upper header pins. The depressions form support surfaces for supporting at least the corresponding upper header pins during high-pressure operation.