Good advice on modifications is to never go cheap on it. That doesn't mean not to buy used performance parts, but don't go the route of doing something cheaply to gain nothing. Most people get a larger diameter exhaust from the catalytic converter back, SVT header, a quality air intake and a good tune would really wake up the car. Also at a 145,000 miles on a Zetec, it is just breaking in the motor lol. As long as your motor was well maintained and taken care of you shouldn't have any problems with the lifespan of these motors.