It's actually a factory supercharger. Those were a short run of 3.8L V6 supercharged cars (I had one). Intercooled, supercharged, gobs of power.
Edit: Woops, I see it was already posted!
I loved mine. Tremendous power and decent gas mileage. I had the 'cougar' version which was essentially the same car, but with Cougar logos and the 'SC' logo.