It is the same thing I've been posting, nice to have some confirmation. I do dissagree to some of what was said, but the general gist is right.
From the KB thread
"Ok, I have a theory. As some of you may know, I am an electrical engineer that works primarily as a mechanical engineer in hydraulics and pneumatics. Working with hydraulics and pneumatics, I am very familiar with pumps and their characteristics. Both the Eaton and the KB are air pumps. The KB is may be better characterized a compressor. Both are commonly referred to as "positive displacement".
A positive displacement , or fixed displacement pump, pumps a given volume based on it's speed and inlet conditions. The outlet pressure has a very small effect on the volume of whatever a particular fixed displacement pump is pumping, be it air, hydraulic fluid, etc. The pumps that I am most familiar with, that are similar in design to the Eaton and KB, typically have a volumetric efficiency change of a few percent when going from low pressure, say 100 psi to high pressure, like 3000 psi.
Now the blowers we are talking about, especially the eaton appear to me to be definatly more "leaky". Especially the Eaton with the roots design being prone to reversion. By that I mean, a few psi of outlet pressure should make at least some change in volumetric efficiency. So headers, I would guess, in theory should make some difference, since they should unplug the oulet of the engine, which I would think would lower the pressure at the inlet for a given flow. Why this doesn't seem to show up as significant power, I don't know.
The KB, is a screw compressor. The screw compressors I am familiar with used in drilling and mining applications, are happy to run at, and are very efficient up to 300-500 PSI. This leads me to believe that the KB volumetric efficiency doesn't change much over the range of a couple of psi.
Which to me means, if there is a little more pressure in the intake tract through unported heads, or past valves that aren't as open as they would be with a bigger cam, or due to slightly more pressure on the exhaust side due to the factory log manifolds, it doesn't matter. That compressor will move the volume of air based on the speed it is turning and it's displacement. The same, or close to the same amount of air makes it to the combustion chamber, and the result is the same power output.
I do see some potential gain because a blower running at a lower outlet pressure needs less power to turn. I guess, at least according to the KB guys, that amount of power isn't real noticeable."
Is he asserting that exhaust mods will not make any significant HP or TQ changes?
If so, I wholeheartedly disagree. The right exhaust system can increase the scavenging effect from the cylinder during the exhaust stroke. Simply stated (mainly 'cuz I'm a simple person), this gets more of the burned fuel mixture out of the cylinder, so there can be more fresh incoming air/fuel.
However, there is a point of dimishing returns.
I don't understand how he explains people seeing 15, 25 or 35 hp gains on the dyno from just exhaust mods.
I think that exhaust works to a point. I think that x-pipe and catback are very solid, sound mods for the 03.
But perhaps headers are just too much exhaust efficiency? If the duration on the intake valves only allows for so much in per combustion cycle, there's only so much scavenging needed on the exhaust side?
Maybe we get all the scavenging we need with xpipe and/or catback?
Maybe with the right cams, headers would make a HUGE difference. I know that they do on other cars.