I melted my cover onto my right head pipe several years ago.
I let it cool completely overnight. Next morning I started my engine with razor blade scraper in hand, and held my bare hand on the header pipe until it was uncomfortable. I then scraped at a near flat angle and was surprized to see a big chunk of plastic come off intact. The residual stuff was removed immediately after with a xylene (Xylol) soaked rag while pipes were still warm. I used simichrome polish afterward to remove the haze. Hope this helps if I'm not too late.
