Under which loan program... sorry, but unless we had a specific scenario of the borrower, there are two many programs and scenarios to talk about. Sure, if I had the weekend to answer this question, but not right now. Way to many variables without having some specifics...
You need to check with that particular lender and see what they will allow first, as the 2nd lien. Each program has it's limit and many lenders have overlays. This is a bold question to ask just anyone. In all honesty, who cares about the rate right now, when the focus should be, will the primary lender allow it and at what CLTV.