Thank you much appreciated!
Note that the SCO drives made the pre-engineered 5A FSD pretty much essentially obsolete, so there's little incentive to get it anymore. The SCO 5A FSD gives you a tiny bit more jump range than the pre-engineered one, so there's really no reason to use the latter.
The main difference between the two is that the pre-engineered FSD is actually double-engineered: It has both the "increased range" and "faster boot sequence" engineerings applied to it at the same time (something that's normally impossible. Also, it's that second engineering that gives it that 5 LY extra jump range because it, too, increases it a bit.) The latter engineering reduces the boot time of the FSD from about 10 seconds to about 2 seconds.
Boot time shouldn't be confused with charge time, though. Boot time means that if you disable the FSD and then enable it again, how long it takes for it to become available. Normally that would be 10 seconds, but with the engineering it only takes 2. There aren't many situations where you really benefit from that.
You need this in PvP when your FSD gets knocked out by Thunder Missiles and you can't do HighWake.