Here's why:
* Dual Exhaust: A dual exhaust system might slightly improve engine breathing at higher RPMs, potentially leading to a marginal increase in horsepower. However, this gain is usually negligible and won't translate to better gas mileage in everyday driving. In some cases, a poorly designed dual exhaust system can even slightly *decrease* fuel economy.
* Spark Plug Change: Using the correct spark plugs as specified by the manufacturer is crucial for optimal engine performance. Using a different type or heat range of spark plug might offer a slightly improved spark, but it's unlikely to noticeably improve gas mileage. Again, any potential performance gain is generally minor and not reflected in improved fuel efficiency.
To improve gas mileage on your Sport Trac, focus on these factors instead:
* Proper tire inflation: Under-inflated tires increase rolling resistance.
* Regular maintenance: Keep your vehicle well-maintained, including regular oil changes and filter replacements.
* Driving habits: Avoid aggressive acceleration and braking. Maintain a steady speed on the highway.
* Aerodynamics: Reduce the drag on your vehicle. While this might involve larger modifications, it is a more effective way to improve fuel economy.
In short, while changing spark plugs to the correct type is essential maintenance, adding a dual exhaust and changing spark plugs are not effective ways to improve fuel economy on a Sport Trac. The money spent on these modifications would be better invested in other fuel-saving measures.
