I just recently bought a calmini exhaust for my 2002 se 4x4 and i want to know where i could find an aircharger for it and if it is worth the expense and how much do they run.

Welcome to XOC... this topic has been covered a few times... first, check out this site:

http://xterraownersclub.com/reviews.html

second, go to SEARCH and look for filter charger under Performance... remember... always SEARCH before you ask, cuz the topic has usually been covered a million times before... good luck on your X...