I took the end cap off the stock muffler and cut through the stinger inside, taking about 3/4" out of it, then left the rest alone. It's no louder than stock but it is a simpler path for the gases to escape. I think it runs a little stronger.
The head can be replaced with a high comp head, simple and gets results, but they do cost money. The tuned pipes get good results but they are a bit more money and a fair amount of work to install and tune.