no only turbo or supercharged engines, they release pressure from the inlet manifold when too high or when the throttle butterfly shuts and boost has nowhere to go.
if not fitted this creates back pressure which causes damage to the turbo shafts and stalls the impellers, then you need to spin the turbo up again to get back to full boost.
What is it with this fascination with blow off valves?
They are simply a safety device for cars with a turbocharger or supercharger - they are not a performance enhancement of any kind - if anything, they hinder the performance by limiting the boost pressure in an effort to keep the engine from spewing its internal parts all over the highway.
