why does everyone say use the stock? If he wants the sound, he is entitled to it.
It's all about the setting of the BOV. I got a Greddy Type-S and my car doesn't stall at all! It's all about adjustment, tighten the spring and it should stop stalling, but don't tighten too tight otherwise it'll flutter and the BOV isn't actually doing its job.
The only side effect of an atmo BOV is that it'll be rich when the BOV vents, and you may get a bit of backfire, especially after letting off on hard throttle.. but being an auto, you won't get rich conditions on gear changes.
having said that, yeah, he should get flamed for not searching.