You only need a tune/chip if you go with a turbo/supercharger/nitrous kit or a 3L swap. You will not get anything from a chip/tune on a stock SVT or one with bolt on mods.
SCT sells XCal 3's which you can get tunes for. The XCal will flash a tune into your car. Ideally you would want to find a local dyno shop to tune your car on the dyno. Your looking at over $500 for a tune.