Can get the Triumph TORs(Triumph Off Road) tune for them from the dealer. Need the Triumph low restriction foam air filter and TORs exhaust before they will do the tune to my knowledge. Any lower restrictive exhaust upgrade should also do like Vance & Hines or Remus. No one else makes an air filter for these two models as far as I know. The K&N will not work as it was for the other T'birds. Slightly different airbox in the LT and Commanders due to different frames from the regular T'bird. There may be something else out there now as I have been out of touch with the aftermarket for these bikes since I traded mine.
It wakes the Big Birds up a bit, but nothing dramatic. I had it on mine and liked it with the Triumph TORs pipes. Was not loud or obnoxious. You may get differing results with the above aforementioned aftermarket pipes. The Triumph TORs pipes look identical to the ones on the Commanders.