I was thinking of running one of those single speed chain tensioner things but have had no luck finding one I like for a good price so I may just put the derailleur back on.
I decided to make a baffle for my tailpipe since it's a little too loud for me. After researching a little on the web I came up with this.
It's a 3/4" copper pipe that I put five cuts in with a hacksaw. Then I heated it to glowing and quenched it in a bucket of water to make the copper soft. I used a nail and hammer to punch in one side of each slit and it's done. It slides in snuggly and it fastened with a self tapping screw through the tail pipe and baffle. It makes my exhaust note a little less harsh.