This link will lead you to a web site which includes a manual from Nissan that explains with ilustrations what Nissan did to improve the GA16DE engine:
http://www.smartnouveau.com/Sentra-Pathfinder.pdf
(wait a little while it downloads)
Apperently, it was intended for Nissan employees only, but it is very easy to read and it has good ilustrations.
Unfortunately, Nissan doesn't offer and sell this improvements for the GA16DE engine.....
Thanks for reading
