Sub-frame connectors... Please build them correctly!

If you study it long enough you can take it one step further with gussets, then one step further with X bracing, repeating until the car is solid as a tank. Can it get too rigid ? Maybe Tall buildings can ( I'm no engineer either ).
if you added any connectors in any fashion and you are happy with the results, that's all that matters. If you aren't happy with your results, suggestions will be in this forum somewhere.
I'll weld the doors closed and solid all around to see what difference that makes. May not need subframe connectors at all. LOL