From what i've read mugen are very credible for extended batteries, as are momax. Momax make a 1800mAH (to my best memory) which is the same size as the normal, or the 2700mAH battery which is a little thicker, but apparently gives a very good battery life
So is it ok to use such battery (2700mAH) with our device? I was always afraid of that for some reason