After having started hacking into my new SD headers... I disagree. I bought a pacesetter weld-in flex to replace the one that came with it. After staring at Intrigue's pictures and trying to assemble the pieces on my jig, it is short a few inches of pipe. Staring and arguing with my uncle about how to make it work, we came to the conclusion that Intrigue used a slip-on flex which has roughly 2 inches of pipe on both sides and provides pipe to slip into the race-pipe/cat. This may have been obvious to some, but not to me. I will now be sending back my weld-in flex and buy a slip-on.
Just saying so that if somebody else reads this they can learn from my mistake.