I bought the shotguns for my Jackpot, you can install the pipes yourself and then take it to the dealer to have them reprogram the ecu. The pipes should come with a reflash card that you present to the dealer, my dealer charged me $40 for the reflash.
As far as installing the pipes, it's really easy once you get the stock pipes off. Getting the stock pipes off is a bitch, it looks like they use a little silicone on the slip joints and it almost acts like glue. Trying to get the front headpipe off from the rear headpipe is a bitch! My friends and I struggled for an hour trying to separate the two pipes, finally just did what another member recomended; broke out the sawzall! Two minutes and it's gone!
As far as power, everyone is right! Seems its not great for adding horsepower, but I wasn't looking for more power. Just wanted something louder so cars wouldn't change lanes into me or cut me off. I also wanted something slimmer so you could see the custom rims and matching pulley on my Ness Jackpot. A side benefit is that you probably save 20 pounds from the stock pipes, they weigh a ton!
Originally I wanted slash pipes but seems everyone has them, saw the shotguns and it really grew on me. There's a side benefit to the shotguns, here in Hawaii; we sometimes meet in parks and have to park in fields. If you ever have to drive down a gravel lane or park in a field with slash pipes, they will kick up dust all over your bike! When people left the meet, you could tell who had slash pipes by all the dust being kicked up! If you stick to roads and parking lots; not a problem.
Also, you can find good deals on factory pipes on ebay and here, but make sure they are new with the reflash card, if you buy used pipes you need to buy a new card. The card is only good for 1 bike and a new card runs over $100, so make sure you factor that when buying used. Bought my shotguns from a member here, Daveh221, brand new shipped to me for $450; great guy! If you've ever shipped anything to Hawaii, you know how great this deal was!
Hope this helps!