can a leaking bov cause overboost ? reason i ask is a friend of mine has a 200sx and number four has gone pop so could the valve have caused it to overboost .he bought the bov of flea bay but when i checked it out after number four went it wouldn`t hold no vacum he said he was giving it a bit of stick in second and heard a loud pop it blew the exhaust manifold gasket then a lot of smoke...cheers for any input..