# Can someone tell me the effect on performance of overexpanded nozzles?

I understand that underexpanded nozzles lose efficiency, due to untapped potential in the gas before exiting the nozzle, but what happens to overexpanded nozzles? I understand that the pressure of the gas is below the pressure of the ambient atmosphere, but what does this do to the overall engine performance?

$$F = q V_e + (P_e-P_a) A_e$$
Where $P_e$ is the exit plane pressure, $P_a$ is ambient pressure, and $A_e$ is the exit plane area. $qV_e$ without the correction term gives the thrust when the exit plane pressure matches ambient. Here $q$ is mass flow and $V_e$ is exit velocity.