Don't mean to be disrespectful of your request not to reply unless directly experienced, but you will probably not find anybody here who is.
As a believer in the laws of physics I can guarantee you that the only way to cram enough air into a running engine to give you a meaningful boost is to do the physical work required to shove that much air in there that quickly. That takes many hp. The entire electrical capacity of a typical car alternator is around 1hp.
You might get 8psi at zero airflow, but as soon as the engine starts drawing air it will go quickly to zero and then negative.
I didn't read the whole thing, but this looked interesting:
http://www.turbomagazine.com/tech/0406tur_knight_turbo_electric_supercharger/index.html
The guy got into building electric superchargers like this machine you're looking at, but much more powerful:
"...they made one that produced 5-6 psi spinning 7000 rpm and drew 700 amps at 12V and 400 amps at 24V. Then he mounted a 6-inch, two-groove pulley on it and attached everything to a piece of plywood in the back of his '72 VW Beetle. Running two batteries in series, he routed a 2.5-inch pipe through the rear firewall. It made 6-7 psi at launch and 3 psi at redline. "The VW was fast," says Knight. "Belts flew off every run; no exception. V-belts don't like 30,000 rpm. I tried for years to do better."
So they got 3psi at redline from 700amps, about equivalent to ten alternators running at full steam.
Later,
"In 1996 Knight looked into a 90-hp DC motor, but it was bigger than a car engine and weighed 1000 pounds. He decided to lower the engine size to a reasonable amount. Even a 2.0-liter engine making 15 psi at 8000 rpm required a 30-hp DC motor. Knight looked into smaller motors, which were still too big and heavy."
That all makes sense. A cool but impractical experiment. What is a motor run off regular alternator output going to give you? Nothing.
