tuning isnt worth it with just a catback...get a couple other mods and then try it. you will need an saf-c to tune though(or something like it).
to reset your ecu, take the negative wire off your battery and push on the brake pedal until there is no light showing up. this is to get rid of any residual electricity left in your cars electrical system. then just put the cable back on, and remember, it takes a while for your car's ecu to adjust itself to the new mod.