I have really thought about this. What about the 'more air in means you need more air out' theory? I am not really interested in a complete exhaust, but I thought I would need a more flowing muffler because of the intake.

 

Not true

 

Without confusing you much more, any engine will only take in the air that it needs. Those needs are restricted from the factory for emission reasons and to make all the hippies happy that want a quiet engine. Putting on a CAI/catback will let the engine breathe the way it was supposed to...but it won't be a huge gain because again the engine only takes in what it needs. Without forced induction to force air in or heads/cam, stroker etc to raise the engines needs for air you won't get huge gains.

 

I believe a lot of your happiness with your upgrades have to do with how long you have been driving your truck. I am very particular about my truck, so when I decided to do my mods, I knew exactly how much would respond to a situation at any given time. So with that said, if you know your truck well, any intake coupled with some sort of exhaust, you will notice a little difference. At anything, you will be so pleased with the sound of your truck, you wont be care too much. I even added a worthless throttle body spacer. All that did really was make a cool whistling noise.

BUT...

With CAT back exhaust, throttle body spacer, intake, and power wire, I saw great gains in MPG. I went from 8.5-9 MPG in town, to 12-13.5 depending on my driving habits.

I guess Im just rambling now. Put in an intake thats on sale, throw in a magnaflow, grab a 3815 (or is it 3875?), and you will be tickled.

 

Dyno a truck with an intake and tuner, then again after adding a cat-back. I'll bet there isn't 3 horsepower difference. There's just not enough restriction there to make it worthwhile. It'll sound more powerful.

The most power gain is from the programmer. An intake enhances that further since the stock setup is restrictive. Exhaust mods aren't worth the time & expense until you do the headers. Until then it's still just noise.

Would I pay $400 for an intake? Hell no! My $75 ebay setup (single pipe, included filter and divider) is functionally as good as anything else.

 

here's what you need to do, it's the safest way to do everything you said, and get the best gains with no risk of decreasing performance, and at a very reasonable cost:

buy a programmer, either the superchips flashpaq, or diaplosport predator ~$325

get an AirRaid MIT, or make one yourself that is similar. ~$120

get a 24" Magnaflow 3" SI/SO muffler. clamp it or weld it on to your existing 3" pipe. ~$140

For under $600, you can do the intake, exhaust, and a programmer with good (suspected) gains, and no chance of losses.

After all the research I have done on this forum, that is the route that I wish I had gone to begin with.

 

One last question: I was looking at my stock muffler tonight...please confirm my findings: 3", si/so, (OUT is definitely offset but IN looks offset but could be center). I just want to make sure I order the correct muffler.