Well, I went to town on the engines. It took a lot more blocks to get the look I had intended. It also resulted in some empty space, which I filled with thruster blocks to compensate for the mass of the decorative changes. Ultimately the block count went up by a whopping 4000 blocks, up from 10,000! It is illustrative that the offensive power or defensive shields did not change at all. The thrust did go up a good bit however, appropriate I suppose given the enormous engines.