Another very popular highly customized ROM is the MIUI ROM. It possesses many extra useful features not found on stock Androids such as enhanced notifications drawer, enhanced camera/gallery/music apps and smart dialing along with a distinct look.
You have to make sure that your phone has at least 200MB of free space and is fully charged to last through the entire process that can take up to 10-15mins.You will of course need a rooted Samsung Galaxy S II to install this custom ROM. You must backup all the user data present in your phone since chances of data loss or corruption are there. Having a backup can help you replace the lost data if any damage occurs. Follow the link posted below to backup and restore all your data easily.
Steps To Install MIUI ROM:
Step-1: Download MIUI 1.7.29 for your Galaxy S II and connect your phone to the computer via USB cable. Copy the .zip file downloaded in the previous step to the parent directory that is to the root of your phone’s SD Card and disconnect your phone from the computer after you are done copying.
Step-2: Download ROM Manager and install it on your Galaxy S II. Now open ROM Manager, tap on Flash ClockworkModRecovery and select Samsung Galaxy S II from the smartphone’s list. Your phone will reboot.
Step-3: After rebooting is complete, again open ROM Manager and tap on Reboot Into Recovery. This time your phone reboots into a special mode called the ClockworkMod Recovery Mode where you can see different options. Here you can make a backup of your smartphone’s current state by scrolling down to backup and restore using your phone’s Volume keys.
Step-4: Backup process takes time so wait till the process completes and then scroll down to wipe data/factory reset. By using volume keys/home button scroll down to advanced and wipe Dalvik cache.
Step-5: To flash ROM, scroll down to install zip from sdcard > choose zip from sdcard > MIUI-1.7.29-SGS2-beta32.zip. MIUI will now flash on your smartphone and it doesn’t take much time. Go to the main menu of CWM Recovery and reboot the system.
The custom ROM is in its beta stage as there are a few things that do not funtion properly. So it is better to have a backup for all your data before performing flash. The above process has already been tested on Galaxy S II and has been confirmed to work. So cast out all your worries and have a safe flashing