If they don't slide together than how can they be clamped together? That doesn't make any sense. I think Vibrant goofed and forgot to put a flange on that part or another connector of some kind. Or maybe they are magic and like in Terminator 3 will just turn into liquid and then solidify as a whole
Keep us posted on your trials and tribulations. If you can get some pics at the mufflershop with your installed system on the car from underneath that would be cool!
Overall it looks like a very nice high quality system.
Just wish they would have thought it out a little better. Of course like most exhaust cat back system this one probably didn't come with any instructions.
Good Luck tomorrow with the installation. Let us know how much they charged you to install it.