Baffles for Yoshi Exhaust

[Lucky 85]

Hi all, I have a set of Carbon Fibre Yoshi mufflers on my 'busa, and have a set of baffle or sound restrictors that go in the rear end of each muffler. They have holes to fix them with something, but not screws by the looks as there are no threads. I am presuming that they are supposed to be pop riveted in place. Can anyone confirm this, and if so, are there any particular types of pop rivets that are supposed to be used?
Cheers
Pastor

I would have to ask why you would be putting the restrictors in, what sort of mufflers are they and are they too loud? I have R77 slip ons unrestricted and I would have liked them to be a little louder. I have had no problems from the local even though they have said if they can put their batten down the pipe then a defect could be issued.