The Thai's aren't really into roids where Muay thai is concerned, but they are into their high caffine drinks like M-150 and Carabao Daeng, like our red bull.
If you're serious about your Muay Thai, save up and go to Thailand to train. I trained out there earlier this year and believe me if you train in that heat, in that humidity you're gonna improve.
All the Thai's are lean, almost skinny - you get the odd tubby one - and they're hard nails. Muay Thai is as much about taking it, and smiling, as it about dishing it out. As one of the other guys said, work on your explosive power and keep it basic. Also, work hard on body weight exercises like dips, chins and burpee's... i think i've spelt that right? Work on your clinching and knee's.
Stamina, endurance and a warriors heart!
As the great man himself said - Muhammad Ali - "Champions aren't just made in gyms, champions are made from something they have deep inside them - desire, a dream, a vision. They have to have the skill and the will - but the will must be stronger than the skill."
Think before you start taking any preformance enhancing drugs, i'm no angel myself and i judge no one, but it's a slippery slope my friend. 'Personally' it take a lot more effort to be clean and stay clean these days, but it's worth it.
this is where i trained:
Lanna Muay Thai
It's an experience i'll never forget. ..... and when i'm old, pissing in my pants and talking to the wall, at least i'll be able to say " i did that..." Clean!