Originally posted by RedSVT:
Dan you are incorrect about no proof, it has been proved and documented many years ago that long tube EQUEL lenght headers DO boost tourqe. The problem with all the coments being made nowadays[ie they dont seem to work on this car or they really dont help]is the fact that they were built with NO regard to correct and proper design! Did you know that making a set of headers with the primary tubes as small as 1/8 of an inch to large can cause as much as a 50 ft. lbs. drop in torque as compaired to a set with the proper dimension? Thats why I asked for the dimensions on the headers, so I can do the math. I bet you there not even close! 
I tend to agree with most of your observations. I feel the 50ft.lb. loss due to .125" over optimum primary tube size is a
rare exception. Though certainly not impossible. You didn't however say it was common, so fair enough.
As for "equal length long tube" primaries. Are they ideal? Sure. Are they realistic in much else
other than purpose built vehicles? Almost
never. They're easy on a rail, or a jet boat
with headers rising above the engine etc.
The problem is to package them in "tight"
engine bays of todays cars and not do major
reconstruction to everything around the
"long tubes".
Now lets look at the equal part again. Does it "automatically" ensure equal FLOW? No.
The reason? The NUMBER of, and DEGREES of the BENDS placed in EACH tube for it to arrive at the collector with the others in it's respective cylinder bank. Once they are
"fitted" into a street car they are rarely if ever the same shapes, and that WILL effect flow rates. Sometimes slightly,
sometimes substantially. It all depends on the amount of compromise to make them "fit".
I don't dispute their worth when properly made. My only thought is that I don't agree
that they MUST be equal length to work properly. You must strive to get them to FLOW equally in an AS FITS configuration.
Maybe they wouldn't be as tough to do in a tour due to transverse layout with respect
to collector location. I don't know. Any thoughts on my ramblings?
