If you plan on modifying, pretty much every mod will require a tune other than a catback exhaust. Most people will do a few things at once before a tune that way you get more power for buck on the dyno. For example the term stage 2, often refers to a turbo back exhaust, an intake, and a tune. Do not throw an atmospheric blow off valve on it to sound cool, it will hurt your car in the long run. Check the oil regularly, keep up on maintenance.
Any specific questions ask away. A lot of very knowledgeable people here.