exhaust keepers and aftermarket pipes

I picked up a 4 into 1 off ebay about a year back, it was listed for a 650...but when i went to fit it the other day i noticed that it would not go into the head with the exhaust keepers.



The pipes have a thick large ring built into them where they meet the head, which is why the keepers don't fit correctly...

Is this pipe meant to be used without the keepers?

orrr was it a pipe for a bigger bike that was miss listed!

There is supposed to be a ring for the keepers to go against. Is the ring to thick, are there any old gaskets still inside head? Do the flanges fit ok?, do they slide over the studs? Can you provide a pic of the problem?