From a Stillen catback? If that's what they're claiming, your should run for the hills.
A mid-pipe (secondary cat delete) could get you those kinds of numbers. But not a catback.
Stillen has burned themselves in the
Stinger community. They had a horrible roll out of their intake (taking money for pre-orders and changing the release date weekly, one part of the company blaming other parts of the company, etc). When we (customers) finally got the intakes in hand we all noted how horribly ill-fitting they were. Many people returned theirs for a refund.
Flash forward a few months, they decided to try their hand at a catback. They announced they catbacks were in stock and ready to ship. There was a
single person on the forum who was brave enough to order it. After about a week they told him it wasn't available yet and they didn't know when it would be ready to ship. Of course he canceled his order.
Since then the Stillen rep has vanished from the forum (they haven't posted in nearly 9 months) . No one on the forum is running a Stillen
exhaust. And when new "best intake" threads pop up (nearly weekly) Stillen is never mentioned.
Apparently they are a big thing in the Datsun/Nissan/Infinity community. Maybe they'll redeem themselves with you guys. I don't think they have much respect for the Korean 3.3tt market, though.