Hi
I have purchased the E.JAN FXX conversion kit and the Ferrari Enzo, I also purchased the Tamiya FXX. I have also read reviews about the conversion kit and they say that the white metal parts such as the engine are copied from the Tamiya FXX kit, don't know if it's true. The conversion kit is very comprehensive, but the instructions are vague, if you go for it try http://www.modelersite.com/Pdf_notes.htm for a build using the E.JAN conversion kit (although they do use a FXX for the build not the Enzo?) There is a fee for the pdf file - 7 british pounds--11.19 US dollars at current rates.
If you go for the Tamiya FXX i would suggest Hobby design photoetch set HD02-0027.