Okay, did some searching this morning. I had asked about variable intakes on
the 4th gen series and finally registered over at maxima.org:

My primary search  (searching at m.org is down):
http://www.google.com/search?q=variable%20intake%20site%3Ahttp%3A//forums.maxima
.org&ie=UTF-8&oe=UTF-8

The FAQs:

http://forums.maxima.org/showthread.php?t=217001
http://forums.maxima.org/showthread.php?s=&threadid=21576

Here's a graph someone posted with dyno results of pre and post MEVI
installs...

http://mywebpages.comcast.net/stevtecv6/dynos/MaximaG4IM_USIMvsMEVI_HP_SM.jpg

The reason I'm looking at this, is because I feel the Max is "almost" there,
but not quite. I can sense a bit of restraint under the hood and want to
explore a little more. Now that it has past 60K miles, I think it is time
to begin the mod process.

Gotta look into the ECU idea, too. I had one for my Jimmy and liked it.