Some clarifications.
KG does not make their own headers, or at least did not last I knew.
They got headers from a european supplier and there were three different versions for the B18/B20. At the point that I stopped getting headers from Europe, KG was changing to another supplier. Although the european 4 - 2- 1 headers were a far better design than the headers available here ( the US ) in terms of performance, I was not happy with the quality ( quality control ) of the headers we were getting. I had to do quite a bit of grinding to make sure they would fit the head bolts, etc., and they would not fit with all intake manifolds, cars setup with negative camber, etc. That is why, among other things, we are now having our own headers made in the US. Its taken a year to get the bugs out of the design and produce a header that has as much of a universal fit as possible without sacrificing performance. We will finally have them in stock starting next week. Everyone who has seen them so far agrees that they are of far better quality than the headers we were getting from Europe.

As to the shorter secondary pipes. There is now a US maker who is offering a cheap, short, header. Ask him to show you his dyno numbers. He doesn't have any. It's easy to make cheap headers, or any part for that matter, if you don't do any testing.
Shorter secondary pipes will move the power up the rpm range and give you a narrower power band - not normally what you want for a street car.

John
v-performance.com