I WANT TO REPLACE MY OLD DECREPED EXHAUST. I WOULD LIKE TO DO IT MY SELF OR TAKE IT TO A SHOP. BUT SHOULD I REPLACE THE MANIFOLDS OR LEAVE THEM. I WAS TOLD HEADERS MAY HELP WITH MY GAS MILAGE. IF ANY BODY LIVES IN NORTHERN NEW JERSEY AND CAN RECOMEND A GOOD MUFFLER SHOP THAT DOES CUSTOM WORK I WOULD LIKE TO KNOW. THANKS IN ADVANCE

 

First off, welcome to DF! I'm hoping you are considering dual exhaust rather than just putting a replacement stock one on. For this, I reccomend sticking with Flowmaster; it's by far the most popular exhaust for Dodge Truck inthusiasts. The 40 Series is the most popular because many want the loudest rumble they can get. However, I recommend the 50 Series. Unlike the 40 Series (made of aluminum), the 50 Series muffler is made of stainless steel and provides a much quieter interior ride; still producing an impressive exterior noise. Just keep in mind you'll be listening to this all the time. Doing this should improve gas mileage considerably.

As for the headers, they will help reasonably, too. The only problem is they cost a good bit. They help improve mileage because your air flows through this piping. Stock headers do not allow the best of air flow, so aftermarket ones are bought with designs that allow for maximum air flow using gently curving pipes. Definately look for the long headers instead of short 90' headers.

In addition to headers and exhaust, you may want to look into a cold air intake system for the ultimate air flow; and to also increase gas mileage yet again.