The TTS Mastertune is the product of Steve Cole, the designer of the SERT which was the predecessor to the SEST/SEPST. Basically the MoCo took Coles software, did not renew their agreement with Steve and developed the SEST/SEPST. I am sure I don't have all the facts and details but that is the short version.
Steve took his software, refined it and developed the TTS Mastertune, which by most tuner standards is the current state of the art.
This is the EXACT version I heard from one of the service managers at my local HD dealership. He had to tell me quietly though. I guess he thought he might get fired if he was caught bad mouthing Harley!