SCT calibration is fairly conservative but that isn't the worse thing. The tune assumes you have a stock car and may have some headroom for bolt-ons, I can't confirm this others may.
Why not read all 600 pages you might learn something, I certainly did.
You will need a tune or at least an edit to your base tune for -
Cat-less down pipe, ethanol blends and additional exhaust flow
If your running strictly pump gas then you'll get more timing if you upgrade the inter-cooler, you also might get more boost.
On top of all that, lifetime revisions come with your purchase of a custom tune.