Installing Yoshi Slip on

I got my yoshi pipe yesterday, no work today, so I've just taken the stock cannon off and put the yoshi on.
Took out the two allen key screws on the heat shield. Took out the bolt securing the heat shield clamp to the pipe and loosened the hose clamp on the mid pipe to remove the heat shield.
Took out the bolt through the mounting bracket to remove the stock pipe.
Slipped on the yoshi pipe over the mid pipe, tightened the clamp thing in the right position so as the holes for the heat shield were aligned.
Screwed in the allen key screws to attach the heat shield.
Put in the bolt to attach the pipe and mounting bracket to the frame.
Now I'm left with a little rivet looking thing...


It's about 7mm long.
What the hell is it and where should it have gone?
Thanks!
Took out the two allen key screws on the heat shield. Took out the bolt securing the heat shield clamp to the pipe and loosened the hose clamp on the mid pipe to remove the heat shield.
Took out the bolt through the mounting bracket to remove the stock pipe.
Slipped on the yoshi pipe over the mid pipe, tightened the clamp thing in the right position so as the holes for the heat shield were aligned.
Screwed in the allen key screws to attach the heat shield.
Put in the bolt to attach the pipe and mounting bracket to the frame.
Now I'm left with a little rivet looking thing...


It's about 7mm long.
What the hell is it and where should it have gone?
Thanks!