I just picked up this pair of batteries. 3000mah so its a little boost over stock and fits with stock back.

Turned out pretty well, get to keep a spare battery charged at work so I can swap if needed.

Remember that these batteries can get to 3000mah and fit in the standard case by removing NFC.

http://www.amazon.com/gp/aw/d/B00CXZHXTG?cache=b5c79835a448bfa5a189da259023dfc0&qid=1401368072&sr=8-2#ref=mp_s_a_1_2

$20

http://www.amazon.com/dp/B00CXZHXTG/ref=cm_sw_r_udp_awd_69Seub1ZY5R2J

http://www.amazon.com/gp/aw/d/B00CXZHXTG/ref=ya_aw_oh_pit

2 3000Mah batteries and a charger. I bought em and do not regret it. I can fit the battery and my wireless charger adapter without any bulge.