Differences between Chrome and Stainless Headers

[gsxbarmy]

K7 and K3 header pipes are interchangeable but the stainless ones are under bent by about 2 degrees which means the twin collector points downward when assembled. If you bolt the collector to the engine then the pipes don't sit square at the manifold so exhaust leaks can occur.

All pipes from Nos 1 to 4 in both chrome and stainless were paired for comparison of the angle differences with similar results. The chrome pipes are the one wrapped for protection. I think the example pipes are from No.2 cylinder.
The datum for measuring was where the pipe enters the collector up to the stop ring. At the header end a parallel was placed against the pipe at the end of the parallel so we now have a reference for the chrome pipe. The stainless pipe was placed at the datum point but look at the difference in angle.

Info kindly provided by @Snapey