It runs fine. There was a little black smoke when I first did it, but that was just from what I shook loose drilling. I haven't had any backfiring.
The sound is good. Not to loud at idle, it sounds really good when you get on it. In my opinion it isn't too loud. A few people think it is. Its perfect for me.
You might wanna drill holes first and see how you like it before taking the plunge.