You have Fuelmoto's Jackpot, get a take off stock header from a dealer for the rear pipe. A lot of them throw them away. The Rinehart Slimline Dual's are not true dual's, which is good. They have a "power chamber" that connects the two exhaust providing a good path for proper scavenging to take place. They are a torquey header as a result.
As pointed out American Custom's will alter yours or sell one outright. They are a little more restrictive than the Jackpot and Rinehart header. But a good option.
True Dual's will kill the mid-range. I had a set given to me to develop tunes (the owner went with the Rinehart Slimline Dual's). I can attest you will loose torque and yes it is very noticeable. I could not wait to get the off my bike.
I have been told from a tuner I trust the Bassani TD's tune very well. They are designed differently than Freedom's in that they maintain equal length head pipes. I cannot comment if they suffer from mid-range torque loss, but can't see how they would not to some extent.
I wen ahead and sent my header in to have the cat removed. I've also purchased a Dynojet PV3 from Fuel Moto; I'm still awaiting delivery on both. I still have stock mufflers, but have heard that will help performance if I knock the caps out of the mufflers. Does anyone have intel on this....is it better to knock the caps out or leave them in?