Double post: https://mustangforums.com/forum/conv...g-battery.html
Sorry, I don’t have an answer. There never is a silver bullet for electrical issues. Especially when there is aftermarket components involved. First, I would say to disconnect all aftermarket components to rule them out. If you still have a drain, I’d like to verify how you are physically testing for the battery drain (where you attached your meter leads, were the negative & positive battery terminals connected or not, what you had your meter set to, how long you waited after pulling each fuse before continuing to the next, what amount of amps you would consider excessive). I’m sure you did it correctly, I just want to make sure so we don’t go down the "rabbit whole”.