For further optimization, I would like to call to everyone\' s attention that an empty srb weighs 3.4 Mass units, while a radial decoupldr weighs 4 mass units, so in upper stages, keeping the empty cans on until burnout of the entire stage may be more efficient than dragging up the decouplers. Using this, you may be able to squeze that little more delta-v out of your design. Edit- I win