well I have a feeling its not going anywhere for awhile lol.
hmm engine mods. one thing I would do is put a cone filter on the end of your intake instead of the box. Won't make any intake noise like the zetec does though. other than that its really exhaust and a tune.... and preventative maintenance.
working in the parts business has told me one thing... www.rockauto.com
has it cheaper about 80% of the time and has it REALLY cheap about half the time. lol. plus I collect their magnets.