I have obtained my ED Visa for Muay Thai in Chiang Mai through these chaps. The whole thing was a doddle. If you decide you want to an ED Visa, I cannot recommend them more highly.
[members only]/
TLDR : Answer Summary
The user shares their positive experience obtaining an ED Visa for Muay Thai training in Chiang Mai, recommending a specific gym for the process. Other commenters inquire about similar options in Bangkok, clarify that the ED Visa can be for more than just learning Thai, and express enthusiasm for the training.