According to what I've read from Patrick Arnold, yes, there is a limit.
PA claimed the original 1-AD (not the 1-DHEA being sold) which was a one-step conversion had a limit. All of the 1-DHEAs being sold today are two-step conversion so they should be even more limiting. However, I did catch a podcast where he said 300lb monsters were still blowing up on the old 1-AD overdosing it, but who knows what else those guys were taking. Something tells me not just 1-AD.