I'm a bit surprised this hasn't been posted yet (though mods please delete if I somehow missed it). I haven't tried it, but I'm reading good things about it. Make sure to thank the OP if you try it.
[ROM][JB][4.1.2][UCLK4][TouchWiz] Stock Untouched [09-DEC-2012] - xda-developers
[ROM][JB][4.1.2][UCLK4][TouchWiz] Stock Untouched [09-DEC-2012] - xda-developers