Jig Built Header Companies need continued input regarding fitment issues.
Did you call SW and make them aware of this issue?
I sold many, many sets of headers when I was in that business.
Anytime I called a header manufacturer, and let them know there
was an issue, the first thing out of their mouths would be; would the
customer mind making some measurements for them, so that they
could compare those measurements with their engineering documents.
I remember that on a certain Ford Pickup, I worked with them to
help them change their engineering documents three times, before
they felt they would be able to release a new header for that application.
Matter of fact; they all welcomed my phone call, as they don't make money if products are returned.
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The biggest issue surrounding primary pipe fitment was;
they really did not want to turn the primary pipe down to soon, as it might cost performance.
So if you had to dent it with a small hammer, the cost in performance might still be better, then if they turned the primary pipe downward too soon, as it exited the exhaust port off the head. This is because the primary header pipe is still hot at this point, which means the velocity is still high.
Second reason given; as we move to the rear of the engine, and we attempt to keep the primary pipes the same length, the primary pipes off the head, would need to have a generous radius.
Cheers
RD