This post takes into account removing the largest unnecessary .cod files that get loaded to the device. If you want to see what's taking up the most memory on your device, OS wise, just go into your java folder and sort the files by size (just click on the size lable at the top of the list.) You'll see the jave files sorted by size. There may be other .cod's you can remove, like voicenotes and search, etc., but you won't gain much by removing them as they are at the bottom of the list size-wise. You can likely remove them but since there can always be adverse effects when removing files, I'm not sure the gain is worth the risk. Just my opinion.