I measured the tube before cutting it to put it at the divergent/convergent cone area. The outer tubing hit something inside right where the stinger and cone meet so I was assuming that it was a weld in there but didn't look. I do have the other pipe that I can check to see if it has the same thing.
I'm not complaining as it kept everything from sliding in too far which otherwise would have made things fun trying ot get back out it it had slid all the way too far in. Once I JB Welded the tubes in I used some needle-nosed Vice Grips to hold the tubes in while it dried.
Here's a rough shot of the end result. It's just one that I have handy.

Ah, just the bigger diameter shim tube hit something .... Ok

You will be amazed once you run it, it will cackle pretty good on the bench, but be darn near quiet as a mouse once at speed on the water

Keep us posted on your results.

Sure thing. After one try to get it on the water (pull-starter issues) I'm hoping that it's ready to try again. I usually take at least one camera with me so I'll see if I can get a video shot.