Never pings. On hot summer days I could occasionally hear my z ping on 91 octane at 14psi...I run 22-24psi all day everyday now on e85 and never hear any pinging. But like you said, there is one huge drawback to e85 and that is cold starts. Seb from SZ has been working with me to improve cold starts but being five hours away it is slow progress. This is a wide spread commonly talked about issue among many other car forums aswell. Winter blends may be the only solution.