Thinking about going with headers on my 99 exp. 4.6L 4X4. I have put headers on many cars and have gotten good results with a bit of a gas savings and a fair amount of extra power. Is this the same case with the exp. I have the K&N cold air intake, which help with throttle response of the line. On the highway I don't notice it. After a tank or two I'll see what the gas milage is like again. I had 17.1 at best before the K&N. Now back to the headers. THinking about the steel ones if they aren't to bad. Always had good luck with them. The stainless are pretty steep. The steal ones should last several years as my other ones have. So input from anyone is welcomed. I will be doing some towing and have 355 gears and 26570r17 tires. Don't want to go to taller gears if I don't have to since I'll be doing more driving with out towing anything. And what cat back would you recommend? Not worried about emissions at this point. I figure if I can save gas I'm saving emissions already. But Staying legal would be good if it is just as good in power. Thanks

 

Hey Mike. I would go with Gibson headers. I hear they are quality and provide great gains. As far as I know they are availible in either nickel, stainless, or ceramic finishes. I am considering doing headers on MY98 expy 5.4. I also found some Ebay shorty style headers made by Flowtech or something like that(these are cheaper).
As for the cat back, do you want single or dual exits?
Either way you could go to Gibson(again). I just finished putting on a Split Rear Dual exit cat back exhaust system yesterday. I got the aluminized finish and the install was a breeze, except for one super stubborn pipe which took three hours to take off.

So far: I love it! The sound is nice and deep without too much extra noise in the cabin. The stainless tips look awsome.
I can also feel the power increase off the line and on the highway. From a halt my truck will now actually chirp the tires, and the highway 50-55mph acceleration is more linear.

Anyways, go to gibsonexhaust.com and see what they offer for your truck, Im sure you'll find what you need. I will soon start a thread about my exhaust install with completed pictures so that may help you in the future.

BTW: My truck is a 98 EB with the 5.4, 4x4, no LLS, and 3.73 gears.

 

Thanks for the info. I will check that site out. If you do start that thread let me know, I'll probably start getting stuff here and there. Might be a while before I get it done. A month or so. I hust wanted to make sure it would give me what I expected,which is more horse and torque. Thanks again

 

Sure, I believe the Gibson Catback gives 15 more ponies on the 5.4 though. And the headers are probably around 20-25 hp increase.

 

Hey Green do you have the Dual sport or the Extreme Dual cat back. I don't mind a good sound as long as you can talk in the vehichle without yelling to loud. And if I do the exhaust first would this make it hard to connect this system to the hedders. Another words should i get the hedders first or the exhaust? thanks

 

I have the dual extreme system. It dumps out behing each wheel. The level of noise isnt bad at all. You can certainly talk inside the vehicle even with the windows down! I was surprised at this! Yet you still get that low guttural rumble but without sacrificing practically any comfort. This system wasn't hard to connect to the catalytic converter pipe, taking the stock exhaust will be the hardest because it is probably welded itself in place.
The exhaust system of the expy consists of 3 parts, (starting from the back)
1) The Cat Back system which is:
A. Front pipe
B. Muffler
C.Axleback tailpipe.
2) Catalytic converters.
A. Crossover pipe.
B. 4 Cats. (2 on each side)
3)Headers
AKA Exhaust manifolds.
Both of the systems will be connected to the stock catalytic converters as you can see. The actual cat back and headers will never touch one another.
I think you should do the cat back system first, it will provide more backpressure relief and give off that sound improvement you seek. Only after performing the cat back upgrade do I advise you to get headers. This is so because they will relieve additional back pressure and more ponies. The stock exhaust system is not suited for the higher flowing headers therefore you wont see their benefit until after you've installed a performance catback system. Also Gibson recommends the dual sport for the best towing applications if I am not mistaken.