How much performance gain from headers ??

[jondee86]

I am seriously considering the HKS Super II header for my (RHD) AE86.
The factors that I like are :


(a) It is 50 dia outlet, which indicates to me a street/strip header.
(b) It is 4-2-1 design which is considered better for mid-range torque.
© It has a flexi-pipe built-in.
(d) HKS have been around for a while, and should know a bit about
designing and building a decent header.

The curious thing is, that after extensive research on the interweb,
I can't find a single dyno test or other piece of hard data. Nothing that
proves these expensive shiney things, actually have any performance
benefit over the stock cast iron manifold

And it doesn't seem to matter what brand... none of the manufacturers
web sites that I have visited has a dyno curve, or even a claim for how
much extra power you can expect from fitting their product !!! WTF ??

Do these things sell on bling factor alone ?? Should they be classed
with such other performance equipment as chrome shifter knobs, TRD
oil filler caps and those vortex fins you put in the intake tube ??

So, please help me out with some hard evidence. Has anyone actually
installed a header and made some measurable power ?? I'm not
expecting miracles, but a documented 5% increase would be great

Cheers... jondee86