Ah the wonders of engine mods. First one day i submerged the front end of my truck and cracked my exhaust manifold. Damn, now i had an excuse to get a header. I went with a downey header despite the negative rap. About a year later, I was fortunate enough to score a borla cat-back exhaust for my 2.7 at a local foreign parts store after borla discontinued production of it. Lastly, I scored a good deal on an Ingine intake a few months afterward.
When i first installed the header without the cat-back i noticed considerable low end torque and more power throughout the power band. After i installed the cat-back, again more low end torque and the power felt strong all they way through 4krpm. Finally, when i installed the intake, i notice another gain in top end power. Now i feel a good pull all they way into 4krpm with much torque around 2500 to 3500 rpm. I'm rolling on 31's and when i'm on the getting onto the highway and downshift into third to get up to 75-80 quick, my truck response quite nice. While at highway speeds and in 5th my truck has good trottle response and pick up.
I still run the stock plugs and wires. Although i am anal about cleaning my trottlebody with every oil change i'm not sure if that is indicative of better power.