I dont think they have an open license for tuning Mustangs, since they dont really have a garage or diagnostic equipment. Rodeheaver could probably do it though.
and I checked, speedo tooth gear wont work on 99-04 stangs, have to go through the ecu to retune it.
what kind’ve power are you looking to put down with the v6? I know a lot of guys who have supercharged and turbocharged the V6, and made about 350hp or so, and snapped that stock 7.5" rear like a twig. I would’ve prob bought an 8.8 out of a GT and swapped it on, for the cost of opening up the diff, and installing everything, probably would’ve been a bit more, but cheaper in the long run.