If you install a blow-off valve on a normally aspirated engine, what is it's function? There's no over-run boost to vent, and you won't get any satisfying chuff-chuff noises. So if you install one and plumb the actuator to the intake manifold vacuum, at lift throttle, it's going to open a hole in your intake system that will just make your engine run badly. Bottom line? No function - no performance improvement - no point.
This is just another ricer trick to make folks think you have something you don't, like hanging an unconnected intercooler in your bumper cover. It's your car, do as you please, but all we're suggesting is, spend your money productively on something that will improve the performance of your car, instead of the "appearance of performance." Unless keeping up appearances is your bag, then, what the Hell, it's your money, spend it as you please. Just don't expect a whole bunch of friendly assistance when you come here asking about such things.
Sometimes I come off as a bit of an ass because I'm an old guy who spends his spare time and money building up serious boosted track machines in his garage. It's not hate, but rather personal frustration that so many of today's young people have almost no knowledge of basic automotive performance principles.
"I read it on HonDUHtech.com, therefore it must be true."
I'm on several car boards, and I rarely ever post a naked answer to a question, I also provide some technical background, so my answer has context in real physics and engineering, and my hope is that the reader comes away more informed than he arrived.
Can you find the blow-off valve in this picture of my SVO Mustang?