Oh no...they're dead on assuming you don't mind making ragged edge A/F ratio's, a steady diet of 100+ octane fuel and 23* of timing a regular occurance.
So to answer your question....no, their stats aren't accurate. At least not for your average user running 91-Octane and reasonable timing and A/F ratio's. Either plan on pulleying it for more boost, or look into a charger that'll make that kind of power right out of the box.
I don't mean to derail the thread here, but I have yet to see a
Tork Tech Inc. kit make less than 387rwhp at their advertised 8psi (usually 390-405hp through a stick shift). And that number was on a car running it through an automatic transmission. Upgrade the fuel system, swap the pulley and make sure you've got a short block that'll hold up to the power and 500-550+hp isn't hard to reach.
...did I mention they were about $500 cheaper than the Kenne Bell kit as well?
Just throwing it out there....do what you will with it.