Durham66,
I have done a ton of mods on my plane. But the one you are asking about, raising the gross weight, was done by Dan Denny. Dan changed the wings & struts to model III wings & struts. I spoke with Dan about raising the gross weight to 1050. He said I could easily do that with the wings and struts he installed as long as I went back to phase one testing and did all the proper tests, which I did. My plane now has a tested and notated gross weight of 1050. It has been flown many times at a higher gross than that. Now I am changing the cross tube brace in the cabin ceiling to the same as the model IV, along with other mods.