soldeejay said:
Welcome to the boards and your new Evo. :thumb:
The first upgrade for these cars is the exhaust. Cat-back, test pipe/high flow cat, downpipe; in that order. Here's our guide too help out a little too;
http://www.evotuners.net/tuning-guide/stage1power.php
The pupose for all mods/upgrades is to increase effiecency, power, and performance. Most allow the motor to breath easier and therefore; more air, plus more fuel, equals more power.
I will never suggest a brand. What works for me and meets my goal may not work for you or your budget. You need to seriously think about what you want out of your car, set a goal, and then research what it takes to get you there. Then ask questions to learn more about the part, it's actual effects others have experienced, and the true costs involved.
This site is intended for DSM's, but a lot of the same information applies to us too (start with names and terminology on the left);
http://members.shaw.ca/costall/1000Q/