Hell I could do that stock...

 

Of course you can....

 

i wish they made lt's for my truck...

 

Stop your bitchin', I love my LT headers, but I'd trade you my headers for your live front axle any day...

 

Here's a couple pics
They tuck in quite well. Didn't bother to take one of the right side as you can't see it.

This is about the only way anyone will know what you have.

 

If your getting more low end torque AFTER the installation of the headers you need to check them for a restriction somewhere. The harder pull at higher rpm's and the mpg gain is normal, but less backpressure caused by a your exhaust flowing better should inherently cost some low end torque. Having low end torque gains and high end HP gains from the installation of headers is physically not possible, unless Doug Thorley has figured out some way to cause more restriction at low rpm's and less restricion at higher rpm's, in which case, their "magic" headers will revolutionize the industry.

 

There WILL be more torque lower as the primary diameters will affect that. If they had not experimented with the primary diameter (and actually gone SMALLER than "common sense" would dictate), then yes, the torque would have remained higher but still not optimized since the collector size and length is limited by the cat location. Since there were LOGS from the factory, there was no scavenging and exhaust pulses would affect the other three cylinders before exiting the manifold. This is exhaust 101 and is the "magic" in a well made set of headers.

 

Since your truck was used for the R&D for these headers, for my own research, I'd appreciate it if you would post a set of the dyno's run on your truck before and after the installation.
No need to get defensive, I just called them "magic headers" because when I researched headers for my truck I found both my local performance shop guru (very well known throughout the nation in Hemi circles) and research compiled by the Massachusettes Institute of Technology, as wellas other sourcesto be in agreement that to get one (low end torque or high end HP) with a single mod, you had to lose some of the other.
This is a basic defintion of headers as defined my MIT:

"In a normal engine, once the exhaust gases exit the cylinder they end up in the exhaust manifold. In an eight-cylinder engine, there are four cylindersusually sharingthe same manifold. From the manifold, the exhaust gases flow intoa singlepipe toward thecatalytic converterand the muffler. The manifold can be an important source of back pressure because exhaust gases from one cylinder build up pressure in the manifold that affects the next cylinder that utilizesthe same manifold. This is the building block for engine torque at low engine rpm's. It is important to realize that this same backpressure, while beneficial for this torque or pulling power at the lower end of the power band, is gained at the expense of horsepower, especially at the higher end of the power curve.
The idea behind an exhaust header is to eliminate the manifold's back pressure. Instead of a common manifold that all of the cylinders share, each cylinder gets its own exhaust pipe. These pipes come togetherat a larger pipeknown asthe collector. The individual pipes are cut and bent so that each one guarantees that each cylinder's exhaust gases arrive in the collector spaced out equally so there is no back pressure generated by the cylinders sharing that collector. In many cases this results in a dramatic horsepower gain, especially in the upper rpm range. It is important to note, however, that due to the inherent laws of physics, some lower range torque will be lost. This loss is usually compensated for by the addition of a cam which is specifically ground to produce an increase of torque at the lower end of the rpm band."

Based on this, and other readings, I am just very curious to know how Doug Thorley was able to break the laws of physics. Since the dyno shows I lost a little low end torque in favor of the HP gains I made from about 2800 rpm and up, I would be willing to purchase a set, so I would not have to go to the expense of putting in a cam for the low end torque gains that I seek.

 

I think the problem can be found in one phrase..."basic definition". Header theory goes far beyond the air pump theory, and although the cut and paste you did is great for a beginner grasping basic exhaust concept, when you get intoadvanced engine theory, there is better reading. One of the greatest minds in engine building is Smokey Yunick. True, headers work in conjunction with other components and THEIR design will often dictate exhaust design. Advanced exhaust concepts that change an engines characteristics, are scavenging, exhaust velocity, collector diameter, collector length, primary diameter, "stepped" primaries, and even the arrangement ofthe tubesin the collector. An excellent case in point is the tri-Y header. There is quite a bit on the internet about why a tri-Y works as it does and when it is appropriate for an engine's task.
I suspect you think the headers on my truck added low end torque, and that is not the case. It helped my mid-range and upper rpm (to a lesser extent). It merely made the exhaust flow in that part of the power band more efficient. As I mentioned before, the primary diameters are smaller than one would suspect 1-5/8". This creates more port velocity than a larger tube, but not necessarily backpressure. That is where scavenging comes into play. Flow past one orifice will tend to createlow pressure, effectively creating a "vacuum", and pulling exhaust from that cylinder. This is where cam design comes into play. When you look at exhaust duration and overlap, you'll see that there is actually a point where exhaust will try to go back INTO the chamber. That is where scavenging comes into play. Instead of that spent gas going back into the chamber and diluting the incoming charge, that "vacuum" (actually low pressure, but this is basic) helps keep the spent gas from re-entering the chamber. Everyone has seen the effects of overlap, just not recognized it as such. Theoretically, air coming into an engine would keep the intake clean, right? Then where does that carbon come from on the backside of the throttle body? That's right, that's an effect of overlap and a pulse trying to go out the intake. The intake valve opens just before TDC pushing air (or actually the residual exhaust from the exhaust stroke) back into the intake.
This is all VERY basic and I've taken great liberties in trying to explain a very complex subject. Am I an expert? No, I've just been building cars for upwards of 35 years and learned a little along the way.
I'll post the dyno sheets when I get them from Thorley. The before and after sheets should help you visualize the changes keeping in mind how it was achieved.

 

As a quick follow up... Over Thanksgiving we hit the road, and I made it a point to monitor fuel consumption. The bottom line was this.... after driving 1,253 miles with 4 people, 2 dirtbikes, and all the assorted gear, I averaged 17.1 mpg. One stretch of that was one I make numerous times a year, so I could make an (almost) apples-to-apples comparison. Before the headers, I would get 16.1 mpg with 2 people, no bikes, and little gear. With the headers, I got 17.3 mpg. One thing to keep in mind is that this stretch is in a remote area of the desert where I typically have it cranked up between 80 and 95 mph. (I know, slow down)
Idon't know how it compares with other people's mileage, but I'm quite happy with the results in both power and mileage. All I have to go by is before and after.