I'm guessing you have either the 1.6- Gamma or 2.0-litre Beta II engines in that, but there was a model change in 2006.
My choice mods would be a fast road camshaft, better intake - Hyundai factory intakes aren't the best in the world, so larger pipes and high flowing panel filter will help.
Then you need to remap or get a piggyback ecu, or aftermarket ECU to fully extract your power gains from those mods.