I don't recommend downloading a "custom rom" made by some master hacker in brazil and putting it on your phone....God knows what he has in there. He may even steal your credit card infos....it's not that hard to do. You're installing an entire OS made by someone you don't know, someone who gives no legal guarantees or anything at all and you don't even know his real name. Once something bad happens, maybe your cards get stolen, you can't do anything.
With the original software supplied by the company, you are safe from these hazards.
If you want a custom OS, make one yourself.