Based on : JXD Firmware 4.2.2 V1.5 0313 03/13/2014

Download Maetel´s S7800B Custom ROM Supercharged Pombagira V1 :

List of changes :

Stock AOSP Launcher
1560Mhz Kernel
Right Thumbstick Range 1/-1
Removed unnecessary apps to made a "AOSP clean ROM"
Play Store Compatibility
Android Stock boot animation
Fast Boot
No more Status bar (Hold home to "recent apps" and "Volume - + Power" to take screenshot)
Resolution Fix (Wild Blood and many others)
Rooted
New Mali 400 Drivers
Supercharged
New Wifi Drivers
Deep Sleep Fix
Super SU, Lucky Patcher, Flash, Chelpu´s modified Play Store, UC Browser, quick Boot, Solid Explorer, RD Client and antutu´s CPU Master added.
All Chinese garbage removed

If you want Swap Internal/SD go to Settings/Storage and choose "Select External SD Card" and Reboot

Pictures :

How to install using Rockchip Batch Tool: