I got the car used with 104k on it, but i have no idea if it has gotten a valve adjustment yet. Should i get one done? what does it do?

 

if you're mechanically able i'd check them yourself, adjusting the gaps to the correct spec will improve performance aside from other things..a quick and easy check would be to listen for noise from the head at idle when the car is warm, if you can hear tapping clearly from the head then you probably better adjust them