Experience Best Performance with this Rom
Jellybean System UI
Many Tweaks Added
Best for Hardcore Gamers
NOTE:I am not responsible for any damage caused to you phone
NOTE;Make a backup before installing it
1) Enable USB debugging (Setting > Application > Development > USB debugging)
2) Download only the ROM from above link (1) & copy it to external sdcard.
3) Download the ROM addons from above link > extract it on your desktop > copy the sound tweaks.zip file from extracted folder to external sdcard.
4) Now boot into clockworkmod recovery by pressing volume up + power down at same time.
5) There in recovery mode you will get an option > Install Zip from sdcard, select it.
6) Now browse to external sdcard & choose the S3 CUSTOM ROM FOR MICROMAX A89 which you copied earlier to sdcard.
7) Wait for the zip installation to finished.
Screenshots in attachments