The only time you really need to start thinking about a "tune" is once you add an aggressive heads/cam/intake and a bigger MAF w/30# or bigger injecters. Or when adding some forced induction. The factory computer is more than capable to adjust for the typical boltons. The computer will have problems once you need bigger injecters(30+#) anything below that it's fine. You can add a chip or whatnot for milder combos if you want but it's not necessary. A good tuner can clean up the idle,part and wide open throttle,and for hard starts. If you're just adding the heads/intake/mild cam(most typical cams fall under this) you'll be fine. What are the parts you're trying to add/change? What's your goals with the car? Give as detailed info as you can for better responses/opinions please.
Kind of important info there bud. Lol. You would benefit from some aluminum heads like tfs's or afr's and a better cam but that's not what you asked. Lol. As far as if you swap parts out,you would benefit from a new tune. If you're just refreshing the heads(i.e. Valve job,etc) and not really changing anything,then no tune is needed.