Ah ok makes sense... still though what size pipes are they? If they aren't 2.5" from the headers back you're probably giving up some power especially on the top end. I just feel like with your setup it should sound a bit meaner.
It definitely seems like the car previously had a close-to-stock engine judging by the rest of the setup. You are lucky though there's a lot of potential in your current engine; once you open that thing up a bit more and regear that car will haul butt.