senna555-Well thats hard to answer at this point. I am working on getting some Pro4 chassis and top decks designed-but I might not be the one selling them directly. But I might distribute them if theres enough demand.
The problem with stiffer top decks on cars without bulkheads is it does stiffen up the car, but not to the extent as say on a Barracuda, Assasin or Xray. YOur best bet on a Pro4, TC3, Yokomo, etc. is to combine a top deck and chassis. You get the biggest improvement like that.