Wanam Xposed App can be used to modify any Samsung Galaxy S4 firmware that is running Android 4.2 and above. While it works with just about any S4 ROM, its developer strongly recommends to use it with ROMs with stock user interface, that is TouchWiz. Here is its exhaustive feature list.
Call Recording
4 Ways Reboot (Reboot, Recovery, Hotboot, Download)
Full Color/Transparency customization for Status bar and Notification drawer elements
Secure Samsung Keyboard
Option to keep “Add Call” button with Call recording menu
Disable Camera shutter sound (+Screen Capture)
Flashlight trough volume button UP
Skip Music with Volume buttons
Save Call Logs View
Enable Keyboard Symbols
Enable Hangouts Calls trough cellular
Enable Camera while calling
Unlimited and Customizable Multi-View support
Bypass Exchange Lock check
Notification Panel Customization
Long Home key behavior
Long Back key to kill App (+ white list)
Disable increasing ringtone
Messaging Tweaks (raise limits and conversion)
Disable Scrolling cache
Enable Full rotations
White/Colored Circle Battery
Transparent Notifications panel
Customize Clock format and size
Customize Battery text helper size
Customize Quick Settings buttons number per row
Collapse Quick Settings after toggle
2 line formatted date on the panel header
Dark themed Multi-Window
Disable Boot sound
Customize Two line date header format
White/Black Email App background (Supported on some devices)
Transparent Quick Settings buttons background
Default hidden SMS logs
Add Call button to Logs and Contacts list
Disable Accounts icons on Contacts list
Custimize Wifi AP Clients number
Disable Launcher page rotation
Add Exit button to browser
SMS Automatic input mode
Disable Call number formatting
Enable unlimited Contacts joining
Enable Gallery Rotation trough button
Set default Browser view to Desktop
Hide Wireless charging popup
Hide Full Battery Notification
Clock position Status bar (Hide, Left, Right, Center) (Compatible with I9300 and I9500 only)
NFC behaviors (UN/Locked on Screen ON/Off)
Hide Headset icon and notification bar
Disable TW DVFS
Enable TW DVFS Boost Benchmark mode
Hide Smart Stay, Alarm, NFC icons on status bar
Launcher: Enable Scroll wallpaper and Hide Dock labels
Disable Wake Home button
Use separate Address field on Contacts
Add Fast PIN unlock (to be used with caution)
Added SMS sent time details
Enable Screen ON options on Messaging App
Disable low Battery warning
Add custom carrier label on notification label
Set low Camera battery level
Change System Holo Dark/Light background
Acces hidden Lockscreen shortcuts menu
Disable SEAndroid/Knox notifications.
You can download it from here.