Hi,

A baffle is a device inside the muffler to help cut down noise. What you want to do is completely "gut" the muffler. Open it up and take out anything and everything in there except for the two pieces of tubing that the bolts go through. These keep the muffler from collapsing when you tighten the bolts. Then put it back together, drill two holes for your outlet tubes, and braze or silver solder the outlet tubes in. Here's a couple of pics. The last one is a custom muffler I built for my Katana.

Good luck,
AV8TOR