Motorcycle Repair: Road King Exhaust, hp increase, vance hines

Question
Just picked up an 05 Road King with FI.  Wanted to exchange the exhaust for something with a little more sound...dealer wants $850 for Vance & Hines Ovals, air cleaner kit and computer download,  Do I need all this, and if so, will there be any HP increase, and what will it do to my waranty?  Friends say to go with the Power Commander, but it will void the waranty

                  Thanks in Advance  

Answer
you can change just your exhaust, but I recommend doing the air cleaner kit as well. It helps the bike breath better, gives you more throttle responce and increases the horsepower a little. The down side is you need to do the download or the bike will run very lean. Your waranty will be fine.
Good luck and happy riding
Mike