He must be a bit of a muppet if he doesn't know, I'd have at least kept the receipt!!
Just post a piccie of it, and any numbers you can find on it, if it were a BB/GT type there would be a massive and distinct lack of lag, what does it start boosting at, full boost at ?
It's got the std turbo damper fitted, it may just be a std one or a T34/35, just getting some bull from the owner/seller.
tabetha