I also intend to make some Torque boxes and weld them in afterwards. I was just curious as to what other members have done.
Dayclona: Am I to understand that the strength in the connectors is greater in the VERTICAL plane, I.E. in the case of a 2x3 member, the 3" section being vertical? If so, this is the same principle that all truck and car frames share, boxed or open. Curious though since I've never seen these cars sag in the middle like an overloaded burro. (Strange reference, I know) I thought that the intended gain was to resist twisting in the middle, and the welded connectors are a big help in reducing the deflection between the front and the rear. I have seen cars with bolted connectors that are installed with the wider section in the horizontal plane and wondered if they were effective at all.