Whats te difference between twin and single BOV\'s

[M@r]{]

As the title says really, seen a few cars with twin BOV\'s?  What are the differences / advantages?  Any difference in noise?

[MillSpeed]

Were these cars twin turbo? Sometimes peeps replace the charge-relief valve with an aftermarket BOV as well as the factory BOV.  I have seen some big singles running twin dump valves too, presumably cos they\'re ramming so much air into the engine that a single dump valve cab no longer vent enough to prevent the turbo from stalling.

[kev-yorks]

I don\'t know why there running twin BOV\'s to be honest a single bailey is more than enough even for a GT42. Could be just a case of getting rid of the charge relief valve if they\'ve wound up there boost.
Kevin