Umarex Notos bottle mod?

I have purchased the American made drop block from ebay, hopefully avoiding the "clocking" issues with the other blocks being used. If not, l have a lathe and mill to correct said issues. I also ordered a regulator and aluminum 13ci tank from China. Does anyone have a confirmed weight difference between a 13ci aluminum and a 13ci carbon fiber wrapped tank? Just wondering if we are talking a very large difference. Thanks, Don