Headers will increase Hp and torque, but the increase will start at a slightly higher RPM, and below that, it will be slightly lower... at least according to several dyno sheets I have seen.

Torque on the pontiac is huge at a very low rpm, and stays pretty even. If you introduce anything to raise it, it starts producing torque later, but makes more. So it depends on if you want to squeal your tires with a 2.56 rear, or go fast in the quarter. Personally, I like low end torque, and am actually leaning to olds engines (sacril;edge, I know, but they are overlooked low end torque monsters, like the pontiac.) I personally would rather have 510Ft#@2400 than 550@3800. I like to squeal tire and make 60ft more than actually get to 100mph on the street to prove my point.