[Galaxy S II General] b_sal:
This is my first post on xda, but don´t underestimate me because of that. In fact, I´ve been following all the GS2 sections and read ALL the tutorials since i got my phone a couple of months ago. Never needed to open an account here to do all the customizations on my phone; This should tell a lot about the completeness of this forum (i.e. SEARCH, there´s a 95% chance that your question is already answered in some thread).

In fact i´m baffled by the amount of people that appears to be unhappy with their phones, doing lots of changes in kernels, roms, themes, etc., looking to improve performance, battery life, fanciness or only for the sake of change. In my experience, you won´t get a "life changing" improvement in GS2 only by a software change. As official firmwares get more and more advanced, their performance delta in contrast with custom firmware gets smaller. The only two areas where the gap is still big lies on eye candy and usability. Moreover, with Ice Cream Sandwich knocking at the door, there´s no additional functionality coming from newer Gingerbread firmware versions.

The customization I have done involves kernel and rom, and prioritize stability and energy comsumption over up to date firmware (as i said in the last paragraph, ICS is not ready yet and latter gingerbread versions doesn´t bring anything new). With that, I could achieve a battery life of 3+ days with average use; For demonstration, i´ve just checked my phone and it shows 2 days and 15 hours with 60% charge. Naturally I am not a heavy user, and the phone is deep sleeping on average 80% of the time, but here on the forum is generally assumed that a drain of 1%/hour is very good mark, so i guess this combo provides excellent battery life (0,6%/hour). I can testify it´s rock solid as well - I´ve been using it for almost a month without any FCs or reboots. And this scheme doesn´t involve underclocking at all, so don´t worry about performance.

Unfortunately (at least for the "spooners") this guide won´t have any images, just links to the respective threads - I´m assuming you do want to learn and read to get your information. The main purpose of this guide is to point a safe/fast/easy way of doing all the stuff, avoiding the need to read all the tutorials and choose the best route among many roads that lead to the same place in the end. The target reader is the complete beginner, who has a desire to learn and unlock his phone in a safe way. Naturally i am not responsible if you blow up your phone or something like that while following this guide; I´ve followed this and it works on my phone, that´s all i can say. I will describe here exactly what i did, step by step, since i opened that damned box :)

So without further ado, this is it:

1) Getting root

1.1) Install the samsung drivers and software (KIES) on your computer ( http://www.samsung.com/ae/support/d...d_mdl_name=GT-I9100/M16&srchword=Galaxy+S+II# )

1.2) Download the zergrush exploit (http://xdaforums.com/showthread.php?t=1321582). If needed (and you will), read the zergrush guide on the respective thread. Warning: There´s a chance that your phone firmware is already patched, so this exploit won´t work.

1.2.1) IF AND ONLY IF zergush doesn´t work on your phone, you will have to use Odin to flash CF-Root (http://xdaforums.com/showthread.php?t=1103399). Read the thread.

2) Backup

2.0) Although you can do all the flashing with Odin, i must assume i´m a lazy person, so i bought Mobile Odin from Android Market. It simplifies A LOT the process of flashing things on the GS2, and as a bonus it doesn´t change the rom counter on the phone! (Read this : http://xdaforums.com/showthread.php?t=1347899)

2.1) It´s an excellent idea to download CF-Root kernel for your kernel version and flash it (http://xdaforums.com/showthread.php?t=1103399 - read the thread to know how to find your kernel version), then enter clockworkmod recovery and do a backup of your internal card (http://xdaforums.com/showthread.php?t=1118693).

2.2) After getting root, install Titanium Backup (from android store) and backup everything you need on the phone. Backup the efs folder as well (http://xdaforums.com/showthread.php?t=1308546).

2.3) Store all backups you made in a safe place (that means away from your phone). Pray to the Android gods with faith, and you will never have to use them.

3) Customization

3.1) Download firmware version KK2 (http://www.multiupload.com/PBBE9HBXTS). Flash it, then enter CWM and clean cache and Dalvik. After that, you will lose root, all your customizations and all installed software. PS: Here in Brazil the last firmware version is 2.3.4, so this version still brings many improvements. If you already have a newer version on your phone, keep it.

3.2) Download CF-Root kernel for KK2 (see step 2.1). Flash it on your phone to get root back.

3.3) Install Titanium Backup again and use the backup you did on step 2.2 to get all your software back, including Mobile Odin if you bought it.

3.4) Download Ninphetamine kernel version 2.1.3 (http://xdaforums.com/showthread.php?t=1179814) and flash it.

3.5) Install voltage control (http://xdaforums.com/showthread.php?t=829731) and use it to do the following settings:

* General - don´t change anything

* Voltages : 200 mhz / 850 mv ; 500 mhz / 850 mv ; 800 mhz / 950 mv ; 1000 mhz / 1050 mv ; 1200 mhz / 1150 mv

3.6) Download Bloat Freezer from android market and use it to freeze all stuff you don´t want. (http://xdaforums.com/showthread.php?t=1069924)

And it´s done. You can continue from where i stopped, installing jkay mod for eye candy and more functionality (http://xdaforums.com/showthread.php?t=1154278), trying a custom firmware like Cyanogen, changing your kernel or doing God knows what. If you read all the stuff i´ve linked, i´m sure you can go on with your own legs from now on. The phone is yours to mess with!