Some useful information that I found:
What is a BOV?
ANSWER:
"There is a lot of confusion over what a BOV is and what they are good for. First of all, the name "blow-off valve" is not a very good name. In fact, the Chrysler factory services manuals call it by it's real name: the "turbo bypass valve". Somehow this valve earned the name "BOV" in the turbocharged world and it has stuck. A real blow-off valve is the same thing as a "pop-off valve", which is a valve that will suddenly open and a certain pressure to maintain that pressure (kind of like a pressure regulator). To avoid this obvious confusion, while maintaining the nomenclature of the turbo world, I will refer to the turbo bypass valve as a blow-off valve, or BOV. In a way, the turbo bypass valve does work like a pop-off valve, since they will open at a certain pressure and maintain it (about 15 psi for Chrysler's valves). This may be how it earned that name, however that is not how it is used, so who knows. So in summary, turbo bypass valve = BOV on this page.
On a turbo engine, the BOV is used to relieve the pressure from the turbo output when the throttle is closed. These valves are only used on engines with the blow-through turbo setup. For more information on this, see the Turbocharger Concepts page. The BOV is basically a vacuum-actuated valve that opens when sufficient vacuum is present. Vacuum is supplied by a connection on the throttle body, while the BOV inlet is connected to the turbo output hose. On 1988 or later Chrysler Turbo I and Turbo III engines, the BOV is placed inside that airbox to suppress noise and prevent the BOV from sucking in dirty air.
While in boost, the valve remains closed and the turbo pumps air into the engine normally. Without the BOV, when the throttle is closed the turbo is suddenly trying to pump air against a closed throttle plate. This creates a pressure spike in the turbo output hose and sends a pressure "wave" crashing back and forth between the throttle plate and the turbo compresser blades. The pressure spike quickly slows down the turbo and the pressure wave can actually damage the turbo. On intercooled engines, this pressure wave effect is suppressed but the pressure spike still occurs. When the throttle is opened again, the turbo has to spin up again, creating turbo lag. If a BOV is present, the BOV will open as soon as the throttle is closed, releasing the pressure spike into the airbox and avoiding the pressure wave phenomena..."