check out this thread with the info on when Locoz fitted his JRSC - gives details of the minor mods he had to do to make it fit.
http://www.contour.org/ubbthreads/showflat.php?Cat=&Board=zetecperf&Number=691359&page=4&view=collapsed&sb=5&o=186&fpart=1its a fairly cheap and simple installation which doesnt need internals upgraded and specialist assistance (like you would for a turbo) and it seems that the mpg is still pretty nice, turboed zetecs have pretty poor mpg. plus the JRSC can be easily run from a chip, unlike a turbo which needs more complex management.
its 4PSI as standard, and can be upped to 8PSI with the different S/C pulley but really needs bigger injectors and MAF to work properly on higher boost. and water injection would be handy for the higher boost.
its a shame the JRSC doesnt have a intercooler and it looks virtually impossible to put one on it without major work. the vortech does have a I/C but Locoz tried the Vortech kit on his zetec and it wouldnt fit properly.
hopefully pretty soon i will be the first mondeo with a JRSC!