What kind of power is a 2.5 inch sports system with new extractors going to give a 1.5L '98 Lancer. Is it worth getting?

 

I'd say about a 3-5hp increase in top-end while making the torque band a little broader. It is worth getting only if you plan on upgrading the car later on, a 2.5" system isn't overkill for a 1.5liter engine, but it shows that you're making a serious commitment to power. Are you buying a kit(like Apexi or Greddy) or are you having a shop make it fo you? Plus, you gotta show us some pictures of your car!