The path you should follow to mod your DSM is laid out very well in our Tuning Guide:
http://www.dsmtuners.com/tuning-guide/
You'll find all the info and parts needed in that guide, for both 1G (90-94)and 2G (95-99) cars, including the free mods.
If you'd like to see all the parts available for your car, visit the Parts Catalog:
http://www.dsmtuners.com/parts/default.php
We list out every exhaust, every intake, etc. made for your DSM.