I really hope that I'm not repeating others questions too much, but I guess, this question is somewhat specific to me. I have a 2005 Mustang GT (4.6) and am very happy with it. The only modification I have added is a K&N Drop-In Filter (not a cold-air induction unit). After this addition my gas mileage improved slightly and I looked in several magazines for ways to improve mileage and have seen several adds for 'chips' and 'flash programmers' that claim they will boost mileage and power, and this combination seems too good to be true. What is the catch? Does this void your warrenty, shorten engine life, fry your transmission, make illegal emissions, or some other bad thing? If they do work, how? I have asked this question at the sites making the products and only received partial answers, so I thought I'd ask at a site like this. I'm a true novice with cars, but would be interested in anything that I could easily do that would improve efficiency, speed, or safety without risk of me botching the whole thing during installation, and if you hace any hints, I'd truely appreciate it. I hope I haven't wasted your time.
-Chris