Dse Deep Tubs From 2.75 To 4.75???

[DOOM]

I have been on Mikes custom cars web site looking at Kjells 69 Camaro. Can anyone tell me how he's getting these DSE Deep tubs from 2.75 inchs to 4.75 inchs ?? I can see in the pictures on album five that he extended the wheel lip,I understand this. But what I do'nt understand is ,did he narrow the trunk floor and frame rails?? to get the extra 2.00 inchs. None of the pictures show. Its such a perfect clean fit I would love to do this for the extra tire width and ride hight
Mario