Here is some good info for our little engine that could. Don't know who all knows about this or anything, but if it seems valuable enough, perhaps it can be stickied!

EDIT: Here part 2! Found some performance tips for the 420A!

That information is correct I knew about that site for years I been try'n to tell these guys for years N/A is not a bad choice!
In fact the 420a used to be known as a track terrorist back in the days!
Don't get me wrong a turbo install can give a GST a run for it's money but there's something to be said about a 4 banger that can haul ass too! :)

All of this is interesting stuff, but for those who really know their cars they know that the 2.0 DOHC in a neon is called the 420a but it is not the same motor as the Eclipse. In the neon the intake and exhaust are on opposite sides of the head. Making almost all of the upper half backwards. I have also learned the hard way that when you need/want to replace the head you almost have to be able to look it over before you buy it, because most places offer the 420a head however it is for the neon. Meaning that it is backwards. However the power and part descriptions sound to be fairly close if not dead on, I just dont know if I would go with the tuning advise. basically all they were doing is reducing drag of the airflow to the intake. Where that can be cured with a CAI or even a short ram. both of which are available for the eclipse. Also they were giving part numbers for a lot of different things that I would be hesitant to take due to the fact that they are for the neon not the eclipse.
If anything take the advise of the article, not the part numbers. It does seem to be a good one though.

the neon engine is "technically" not a 420a but an A588