String Tension
You can adjust the string tension on some guitars, the two piece tune-o-matic style is a perfect example of a tension tunable bridge.
If you want more tension, lower the stop bar all the way down. If you want a looser, more slinky feel then raise the tailpiece. You must be aware that there is a certain amount of downforce that is required to keep the strings in proper contact with the bridge, and too much tension will cause the bridge to collapse over time.
The much talked about overwrap of the tailpiece gives you less tenstion on the strings and the added benifit of better tone coupling to the body (the better the bidge/stoptail connection to the body, the better the tone transfer is from the strings to the body).
When adjusting string tension there are a few things to consider.
If you go with less tension, you will have to bend further to reach the same note as you would with more tension. With more tension, the strings are tighter, but the bends are shorter. Too little tension and you might find yourself needing to develop a technique to deal with bending into the adjacent string(s). Too much tension and you might find it harder to tune a bent note as smaller movements will make bigger differences. Tension is a personal preferense, and it should be set up by the player, if they know what they are looking for.
The tone of the guitar may change. Too much tension will put more stress on your neck, and will give you more downforce on the nut and the bridge. Tone coupling is theoretically better with more tension, but better coupling does not allways equal better tone. With most things, there is a 'sweet spot' where things come together.
If you have string tees, you can also adjust the tension by raising (or lowering them = moving their location or shimming them). But keep in mind that their sole purpose in life is to provide downforce on the nut for guitars without and angled headstock.
To experiment with string tension to see what works for you, I would suggest the simple route of tuning your guitar up or down to see what turns your crank.