I have a 99 E/B Expedition. I tow a 30' travel trailer that weighs around 7000# fully loaded. I am looking to get a little more power out of the 5.4. My first install is going to be a K&N Intake kit. Any suggestions for the next thing(s) I should look into?? Thanks...

 

Look for an Ex with a diesel...

 

There is a thread a few lines down titled "newbie with '03 Expedition performance ?'s" about the same basic thing.
The intake along with a good cat-back exhaust and a custom tune WILL provide more power, but the general concensus is that going to a lower gear will provide the same results in a different method. You can read that thread and then chime in there, I'm sure your questions will be answered.

 

Changing your gears to 4.10 will give you more power for towing than all of those other mods. You'll probably see better towing and in town MPG too, believe it or not.

 

x2
Re-gearing gives the best bang-for-your-buck IMHO.

 

I think for now I am just going to add the K&N intake system and an exhaust upgrade. What series Flowmaster would you recommend, 30 or 50? Is there much difference in just installing the muffler or installing the cat-back? If that doesn't get me where I want, I may eventually change up to a 4.10, so we will see.. Also, will I need the Flowmaster with 2-1/4" I/O or the 3"??

 

The best bang for big bucks would be a positive displacement supercharger.

 

K&N intake = $250
Cat-back = $350
Gears: $600 installed

I guarantee you that the truck with deeper gears will out-tow and flat-out beat (in any race) an otherwise identical truck with intake and exhaust mods. Add a chip...you'll still get beat.

Just an opinion.

Intakes and exhausts are quite popular. They were the first two things I did. In hindsight, though, I should have re-geared.

 

Gears may be the option I go with then. Its around $600 to change front and rear gears?? I have 3.73 now and it tows great on average interstate, but slows me down to about 50 - 55 mph on long and/or steep grades, 5% or steeper. So I was hoping that intake and exhaust upgrades would help enough.

 

Thats going to be the best way to make more power. Any other stuff and you are really just throwing money away.

 

Hmmm...you're a 4x4, sorry, just saw that.
Gears will cost more, perhaps double.
And you already have 3.73...in this case, gears may not be as strong as I thought.

Going from 3.73 to 4.10 will net you about a 10% gain in torque multiplication. If you were starting at like a 3.55 or, like me, 3.31, then it may be more worthwhile.

What size tires do you have? If you have large 4x4-type tires, then 4.10 or even 4.56 (if you've got large tires only) would really help you out.

So depending on your tire size, I may retract my earlier statement.

Blowers are great, but they aren't for everyone. I bought my Procharger used, paid like half price for it...I could not be happier with my truck.

 

I thought that $600 for gear swap sounded low, thats why I was asking. As far as I can tell, I would have around $500 in gears alone, + installation. I was also wondering how much that small of a jump would help, from 3.73 to 4.10. The tires aren't huge, 275/65/17 I think. I was talking with a mechanic friend of mine and he recommended the Cold Air intake kit and the Superchip programmer. What do you all think? Anyone used a programmer on their Expy? Hypertech or Superchip, I am curious to know how good/bad they are. A supercharger is just way out of the picture right now, til I sell my boat and 4wheeler to counterbalance the new camper purchase.

 

If gears and FI are not in the cards right now, then a good intake, cat-back and a CUSTOM tune will help you out some.
I found my K&N Series 77 intake on Ebay for $150 shipped, a decent cat-back should run you about $350 (changing just a muffler will give you sound only), and I got my SCT Xcal 2 from MotorHaven for $379 with several custom tunes (one of those can be a tow specific tune in your case).
So for roughly $900 you can definitely add some power, but don't expect a massive seat of the pants increase. The exhaust and intake may give you a little more HP/TQ and maybe a 1-2 MPG increase, but the custom tune is where you'll see the best benifit in the towing area. You can change the shift points/pressure, idle speed, adjust for tire size, advance spark and other things in the tune itself can really help your towing power. For me the biggest thing the tuner did was make my truck not to downshift at the first little rise. Now I can maintain speed in a higher gear, keeping the revs down and effectively saving gas. Of course I have been running the 91 octane performance tune, but the extra cost of gas is offset by the extra 2MPG I am seeing, while still providing a much more responsive truck. When I get on it, it goes!
I would call the MotorHaven guys and tell them what you are looking for and have them recommend a tuner that will work best for you.

I would do the tuner first, then an intake and then the exhaust.

 

Since you are a 4x4 with basically stock tire size and 3.73 gears, I agree with Onespeed24.

If/when you do the exuaust, I recommend replacing the y-pipe/collector. On my 97, and others that I've seen, the inside diameter really chokes-down.

 

Anything here that WOULD NOT apply to an '03 Navigator? Being in the Rocky Mountains, I'm leaning towards a blower. Any recommendations?