By far and away, the least expensive "fix" to get about a 10% increase in power, decrease the amount of heat the exhaust system produces, and just generally get a better running/performing bike is the Fullsac Stage I exhaust system with the TTS and Steve's canned map he will provide for the bike. The parts will cost you approximately $1100. If you have any mechanical skills, you can install it yourself and ride. If you don't, a competent person will be able to do it in 3 hours or less.
You can stick some slip on mufflers on the bike and it will compensate, but if you want the bike to run to it's maximum potential WITHOUT doing ANY engine work, like cams, you must get ride of the catalytic converter in the stock header pipe. This can be accomplished by cutting/welding the stock header pipe (or Steve George will do an exchange with you) or by purchasing the new (and better designed) header pipe. But, if you remove the cat, you MUST modify the stock ECM map.
If you make no further changes to the bike, you'll never need to re-tune it after the initial changes.
I would suggest that you contact Steve George at Fullsac.
http://www.fullsac.com/ Tell them you are a member here and get a discount. This is a PROVEN system that hundreds of people here have used and you can choose the loudness of the exhaust by which cores you choose.