Making A New Exhaust Heat Shield By jon_admin in MX5 Drift Project December 3, 2018 The rear muffler exhaust heat shield on the MX5/Miata has rusted away to junk and is starting to rattle to pieces. I fabricate a new heat shield from a sheet of aluminium and fit it to the mazda. I hope this helps you make your own. Tags: Exhaust, Fixes, Mods, MX5