Yep, about 20 lbs each. It is not noticeable to me any more. It didn't even feel like I had half a passenger, cuz even tho it is probably about 50 lbs of weight, it's all below the seat.
I used all the existing bolt locations under the tail. 8 in all iirc. Battery tray, seat latch, and undertail pan.
The boxes and aluminum frame are VERY TOUGH and have held up to more abuse than they should be subjected to. Including tucking the front twice, Both on the left side as my **** luck should have it.