This is my opinion, so it and about $4 will get you a cup of coffee these days...
By far, the easiest and most simple solution is to go with the Fullsac option. Get the X pipe, it fits like a glove, uses all the stock heat shields without issue, and is easy to install. The Fullsac cores for the stock mufflers come in three sizes...1.75", 2", and 2.25". The 2" cores supposedly give the most power/TQ. They are also a good compromise between too loud and quiet. I have the 2" on mine, and for me, they are plenty loud when you get on it, but not too loud at steady throttle. The most difficult part of the installation is grinding the welds off the stock cores to remove them for the installation of the Fullsac cores, but if you have a Dremel tool with the right bit, and take your time, you can get it done without damaging the stock cans. Leave the packing in the stock can, slip the Fullsac core in, bolt it down, and your done with that part. Get the Mastertune TTS and cables (through Fullsac, or you can get all this stuff through hd-dude(Jim) on this site, at a discount)...if you have a laptop, or access to one, install the software, do the updates, use the MAP that has already been done by Fullsac for your bike, upload the original program from the ECM as a backup, download the new MAP to the ECM, then go riding. Yes, you could take it to a Dyno and have it tuned to get the n'th degree of HP/TQ, but it won't be a significant amount, if any. My bike runs perfectly well with the canned MAP, so I'll save the $400 bucks or so that it takes for a full blown Dyno tune...I can live without 2 foot pounds of TQ, if it's even there to be had.
Call Jim (hd-dude) at Metal Dragon 510-885-9471, or shoot him a PM here on the site. Or, look under the Vendor section and call Steve at Fullsac and get it through them. I just ordered through Jim because I know him, he's a great guy, ver helpful, and will take care of you. I've heard the same about Steve, but I'm loyal to those who have treated me right in the past, and Jim has always done so.