Samsung has officially confirmed (http://www.gsmarena.com/samsung_prepping_a_galaxy_s4_with_lteadvanced_technology-news-6226.php) that it is working on a Snapdragon 800 based Galaxy S4 variant, carrying the model number SHV-E330S. Today we also got a manual uploaded a bit prematurely to give us more details about what the device will be like.
(http://cdn.gsmarena.com/vv/newsimg/13/06/samsung-e330s-manual/gsmarena_001.jpg)
The chipset is obviously new