Tankstar Baxton

Im trying to conver a clasp i made to mesh. Ive built the mesh for it but and set a bounding box by setting 2 vertices at 1,1,1 and -1,-1,-1 and scaling around the clasp. Blender notices this and so i export. But when i Upload to SL the bounding box isnt how i set it but set to normal as if i just ressed a standard prim. How do i keep the enlarged bounding box so i can make my actual mesh a for better lack of words "nano mesh"?