Update your Galaxy S II GT I9100 to Ice Cream Sandwich 4.0.3

Good news Galaxy S II owners, you can now get in on the sweetness that is Ice Cream Sandwich using build XXKP8. Consequently, we present you with the following step by step guide.
Important:

• This ROM uses a custom kernel which is unsecured and will void the phone’s warranty.
• Update your phone at your own risk. Do not hold us liable for any damage arising from your use of this tutorial.
• This update doesn’t need root access on your device. If you have rooted your phone beforehand, updating it will revoke root access.
• If you’re using a custom ROM, make sure lag fixes are disabled from Recovery Mode. You can access Recovery Mode by pressing the Volume Down key and Home button (middle key) simultaneously, while pressing the Power button. While in Recovery Mode, select ‘Wipe data/factory reset’ and ‘Wipe Cache partition.’ Then reboot your phone by selecting ‘reboot system.’
• One final disclaimer. Please note that this is an early, buggy build of ICS and is, thus, not suitable for use as a daily driver. This only works on the international version of the Galaxy S2 and not on the Epic 4G Touch, Skyrocket or other variants.

Prerequisites:

• Create a backup for your files or transfer all your data on your SD card in case it gets erased or corrupted while updating your phone. Don’t use Samsung KIES in creating a backup.
• Disable system tools on your computer such as antivirus software, firewall programs, Samsung KIES, and PC suites. These may interfere while updating your phone.
• Enable USB debugging by going to Settings > Applications > Developemnt > USB Debugging.

Update Time!

Step 1: Download the following files:

• ODIN 1.83 [HotFile]
• Leaked Android 4.0.3 ICS XXKP8 [HotFile] (password: samfirmware.com)

Extract the ICS ROM. Place its contents to your desktop for easy access later in the guide.
Step 2: Launch ODIN.
Step 3: Turn off your Galaxy S II. Once shut down, press and hold Volume Up + Home + Powerwhile booting up to enter Download Mode.
Step 4: Connect your Galaxy S2 with PC via USB. ODIN will detect it.
Step 5: Click on PDA and select: I9100_CODE_I9100XXKP8_CL42141_REV02_user_low_ship. tar.md5 which you placed on desktop in Step 1.
Step 6: Click on PHONE and select: MODEM_I9100XXKP8_REV_02_CL1092599.tar.md5
Step 7: Similarly, click CSC and select: GT-I9100-MULTI-CSC-OXAKP8.tar.md5
Step 8: Click on START.
Step 9: ODIN will now flash the leaked ROM to your Galaxy S2. Once phone restarts, unplug it from your PC.
If you have flashed the kernel after flashing the firmware, or are experiencing force close errors, you probably need to wipe your phone’s data. To do that, reboot the phone into recovery mode. Turn off the phone first, then press and hold both the Volume Down key and Home (middle) button, then press the Power button. In the recovery menu, select “Wipe data/factory rest” and “Wipe Cache Partition.” Afterwards, reboot your phone by selecting “Reboot System.”