Various systems for reducing noise, vibration, and harshness in an intake manifold are provided. In one example, an intake manifold includes one or more runners, a plenum fluidically coupled to the one or more runners, an inlet having a wall thickness, and a first and a second indentation, where the first indentation protrudes radially inward at a first inflection point in a first direction, the second indentation protrudes radially inward at a second inflection point in a second direction substantially anti-parallel to the first direction, and the wall thickness is maintained at the first and second inflection points. In this way, noise, vibration, and harshness associated with the intake manifold and its inlet may be reduced without additional weight, cost, or complexity.