DangerIsland

I'm looking at my exhaust system for leaks and trying to fix my boost problems. My car has a very non-stock setup and I'm trying to compare to a stock one. My question is: Is there normally a join that bolts together (with 4 bolts?) just in front of the cat? Mine is welded there, so it looks like the cat was welded to the pipe coming off of the turbo. I'm going to take it into an exhaust shop here to see if they can find a leak, or see what's going on, but I just wanted to clean up what the stock setup is. Normally there should be bolt-together joins at:

1) headers to crossover.
2) crossover to turbo
3) turbo to downpipe,
4) downpipe to cat?
5) cat to catback/muffler.

Is that right?