You should add your truck to your sig. Then we'll all know what you have and will be able to help you a little easier. I put a complete MBRP stainless system on my '95 and it made a huge difference with power and fuel economy. I coupled that with a Tymar air intake system. As they say, "Diesel's need to breath to make power". I used stainless cuz I live where the road crews add salt to the winter roads, like I add sugar to my coffee...I need to cut back.
The Hauler - '05 F-350 4x4 CC Dually 6.0 Powerstroke
The Project - '90 Ford Bronco 4x4
The wife's - '11 Ford Escape
For every minute you are away from work...you can add two minutes to your life!