From what I read the power tune limit comes into play with these cards at 1.3v and above, even though they will do 1.4v. I think the power tune 20% limit is removed on the lightnings LN2 bios isn't it?
If its true then there needs to be a bios release with powertune limit removed so these can be more useful for extreme over lockers.
As far as I know You can remove all protection on these cards by joining two jumpers in Hotwire section with solder or wire. Protection does not kick in till around 1.45v anyway.