ye..Plenty of 800-1000hp RB26s make their peak power at 8200-8500, and realisticly the heads just arent designed to flow decent amounts of air past that
Edit - to answer your edit, yeah Ive seen a few bent ones over the years, from over revs/det etc...at 400+ they will be the first thing to fail with even the slightest hint of det or an over rev