Proparts headers

Well I was trying to bench assembly my proparts headers today and noticed there's no way to attatch 4 of the 8 pipes to the collectors. The outside pipes have little tabs on the collector and the pipes themselves. but nothing on the 4 inside pipes. Is this enough to keep the headers together? Also one of the pipes is 2 pieces. They just slide together and thats it. I'm no expert but wouldn't I have exhaust leaks here and at the collectors?

The attatched image is just something I found on google. But you can see the tabs on the left hand side.