exhaust and tuning

[BIG CHEVY]

ok......... i got a 350 that i think is stock as it gets. its kinda tired as engines go, but still good.  i am reading in posts that
a new header slash full exhaust system will help performance some. i have manifolds and some ol rusty muffs and pipes that end under cab.
  i do know some  about engines but dont dare take them apart yet.  or at least any parts that need me to understand retuning it.
so my question is..............if i get a total new header/exhaust system,   will the engine still be fine or will i have to adjust anything like tuning?
bear with me guys.  the only way i can know is to ask.   i admit i should know this,  but never had a mentor.  the engine to learn on was always mine and i always had to work on monday.  so i never went deep into them.    thanks in advance guys.

[jd4020]

you might need to adjust the carb a little bit but other than that it'll be fine

[Irish_Alley]

you will be ok with out adjusting anything, but to get the most out of something yes it does have to be adjusted you will be amused what just a couple dec of timing will do