[spacemanspif]

If you are that worried about emissions, start riding a bike on nice days. When you finish the engine build and are getting 4mpg you'll only drive the truck for fun and put somewhere around 5,000 miles/yr on it because of the gas bill thus, reducing your carbon footprint. You'll also love your beater because you can park it in tight spots, whip it around in the city and not care about dings and scratches. Ask me how I know this...and my "racecar" gets a whopping 18mpg!! I don't run cats because I am emissions exempt for the age of the car and the 5,000 miles/yr I drive it is probably not affecting the ozone layer much. Plus, I feel that keeping a car running has a much smaller footprint than destroying one and building another.