the Zetec never had a distributor... did it? those started to get phased out when OBD2 started. I know my 01 came with a coil pack stock...
As far a coil packs go they can allow for a "cleaner" spark so it will idle smoother in some cases. but you don't get a performance improvement when going with a different coil pack. Stock vs scream'n demon vs MSD are all the same until you start getting into the high boost applications. i think its safe to say the JRSC even with the boost kit is a boost application but is not a "high" boost.
2001 ZX3 2.0L Zetec-
Hatch Nation #42
Going through Rebuild See "The TICK Build Thread" for details (http://www.focusfanatics.com/forum/showthread.php?t=289168&referrerid=62897)