Yep, what Mr. Field said. IMO the welds are suspect. The welds on my original and replacement FBF crossovers had severe undercutting and no crown which can indicate the lack of a purge when the part was being welded.
When my first one cracked, FBF said they'd inspect the welds on an new one and send it to me. (took 'em a while
I bought a Stucci to replace it and couldn't be happier. Yes, the Stucci is heavier but it is better built and includes a bung for mounting an O2 sensor. The wall thickness of the tubing that Stucci uses is almost twice the thickness of the FBF. If FBF is going to use that thickness, then it is critical that the fit (I noticed a few spots where they had to force the joint together) and welds are perfect, as there's little margin for error.
Oh, performance-wise, I can't tell the difference between the two...
If you want the boring technical info on the weld failures, let me know...