^+1... usually when you get a tuner say the SCT3 hand held you tell wherever you buy it from what bolt ons you have on the car and they will load a custom tune for you setup. you can also get another tune for added bolt ons, but for big power adders its always best to get a dyno tune.:withhomo
I mean "Technically" you can tune it yourself if you get the specific software that the device uses; but I would never recommend that unless you've A. know what your doing, or B. have tuned a car before.
Canned tunes are perfectly fine for minor bolt-ons, but if you are doing something bigger, cams, s/c, nitrous, turbo; a dyno tune is a 100% must.