I had a tough time getting them to fit together. One was round the other was oval. I think I tapped the outter edge of the front header with a hammer to roll it in slightly. Once it was barely started fitting into the crossover, I tighened the bolts/nuts on the front head a few turns each and tapped the joint area with a rubber mallet. Tightened more, tapped more. When it was all snugged up and in place I clamped the joint down and there was no leaks. :th_thumbsup-wink:
That's the same way I do SLP's and ZZP's, works like a charm. Tighten rear header to head, slide crossover in and then work the front in. (ZZP is skip crossover step, front mates to rear over trans.)