Ok, I tried out the monobrominated PMA and it was crap--it just made for a good stimulant, that's it. Are you SURE the dibrominated stuff is good? What literature reference do you have?!?
I'm not surprised that the mono-brominated version didn't give you what you might had hoped for. However, by extrapolation, I see a possibility for hallucinogenic activity of the 3,5-dihalo PMA. There is some structural relationship with mescaline.
There are two *magic* combination possibilities for the phenyl substituents:
- 3,4,5 (like mescaline)
- 2,4,5 (like TMA-2)
I advise the following book: Hallucinogenic Agents, by RW Brimblecombe. Contains alot on these things, especially explaining why some substituents are great and others are not etc.