The known/documented lean issues were primarily associated with 04-05 and some 06s. However, most of the tuners strongly recommend you get a custom tune for most after market intakes with the 5.4L, 3V motors. Which model intake do you have?
As to upgrading your Evo, please read this:
http://forum.gopowerhungry.com/faqs-...de-my-evo.html
IMHO, the upgrade is money well spent.