Voyager was not designed to do QSD, still it worked for a brief period of time, I guess the Vesta class ships could exchange parts/equipment easier then Voyager to experiment with it. When they have found something like a "baseline" setting, perhaps distribution to other ships could be realised. As far as I can see it, no heavy exterior modification would be involved.
It's like upgrading the CPU, you will go faster, but you still looking at the same old case.
I do think the Aventine/Vesta class should be overbuild though, so it can be used over and over again to test new setups and break new speed records. That way it would be able to serve a long time, like the Excelsior or the Miranda classes.