Anything you do short of installing a larger turbo isn't going to net much power gains at this point. And as soon as you put a larger turbo on the car you can expect reliability to go out the door.
Being an 05, I'm assuming the OEM struts have over 60k miles on them by now? Handling wise, I would start with better springs and replace the worn out struts. After that, sway bars will be the best bang for your buck handling mod.. assuming you have good summer tires installed already.