i don`t have a muffler ( no muffler and new camshafts = great sound), and it`s not a lot of gas, it`s just spitting a bit of gas out the exhaust, and since it`s side exhaust, it will spalsh my neighbours car if i`m not paying attention. Once again this little spitting thing only happens until the engine is hot. Afterwords, it burns it properly. One more thing, how long is a new cat supposed to stink so bad, because after i floor my car, and then stop at a traffic light or stp, it smells like boiled eggs.