When do you reckon Tyson started taking PE drugs

I agree with this statement. I've very recently watched some of his late 80's fights. Frank Bruno was way more cut than him. I think it was natural. I also don't think he would have had the handspeed he did had he been too ripped.

 

I doubt Tyson ever took any drugs in the 80s.

But when he got out of prison, he became very bulky, like a bodybuilder and even when older against Williams and McBride he looked like he was on roids. Just absolutely jacked. And knowing Tyson, who wouldn't probably care if he was cheating or not I think the chances are pretty good he took them later on.