[alexiskai]

The sleeve linked to above is good at what it does, which primarily is helping the muffler and the exhaust manifold line up correctly. It's very easy to attach them so that they're slightly misaligned, which often leads to an exhaust leak. You can eyeball it, you can measure it, or you can use the sleeve.

When repositioning the muffler, be sure your tailpipe clamp is loose (they're designed to be loose).