Dragos or maybe try a mute to create a bit more back pressure to the SE's already fitted, they will tone it down a little however
or talk to these guys
http://www.pipemasters.net/indexfront.html
A Supertrapp muffler or mufflers can be tuned for torque, HP and also tuned for back pressure to suit headers with 02 sensors
I was running the internal disc type 3 inch supertrapp mufflers on my old 06 superglide and was happy with their performance and sound with 14 discs closed cap in each muffler. The bassani road rage on my bike was way too loud for me so I fitted a four inch trapp on it to quieten it down. I was running a differnt number of discs over a few weeks until I found what I wanted 24 closed. The best thing about the trapp is it can be street legal to pass EPA or changed to a open megaphone in a few minutes if you have vtuned maps to suit.
Hilly I would experiment with installing a 1/4 bolt in the header end off the mufflers to gain back pressure like some of the smart tuners used to do to drag pipes. It would be interesting to see if you gain any torque from this simple mod and you could also run it along the perforated baffle with out drilling holes to see if it makes any diferance where its located. Suppertrapp sell 3 inch end muffler cones that would clean them up for the coppers and EPA if you get a hard time.
http://www.ebay.com.au/itm/Supertrapp-Tapered-Billet-Exhaust-End-Cap-Chrome-/370768071362?pt=Motorcycles_Parts_Accessories&hash=item56537fcac2&_uhb=1#ht_2080wt_905
Get all your TTS stuff loaded on a usb stick before your computer crashes. I lost a shit load of maps to suit my bike when the laptop crashed. .