Behl, I must confess that when I saw your sumo photos you posted a year ago of this same fruit, I was thinking about it when I started this post of the largest mandarin.
I do have a large sumo that I thought could be a world's record weight, but yours looks larger. To bad you didn't get a photo evidence showing the weight of it. Just looking at your fruit in the picture and estimating its weight after looking at my large fruit, I think yours weighs about 1.5 lbs. The one I have is 1.3 lbs and I will now post the photo for evidence later tonight.