No, that's not them. That's some squid trying to be cool. Kinda like those d-bags that stick the big ass chrome exhaust tip on their mom's accord. The real ones go on BEFORE the muffler.
Oh here we go. Another muffler bearing -vs- spiral gaskets thread Yes it's true that you can squeeze out like .05% more HP with the gaskets, but with all the added expense of the new filter and intake lube, it really isn't worth it.
The power is trapped with a stock exhaust. So besides sounding better, the pipes will release all that power. That extra power is tough on the exhaust system though. The muffler bearings reduce the strain and lengthen the life of your exhaust system.