Baz,
I put heat shields on to protect my kids before it happened, plus mine look
sh!t hot. Don't want the risk, run a under car system or fakes. As for performance they may rob power but what are you building,
a sometimes race car or a street car. Shelby's Cobras seemed to do allright with sidepipes.To each their own and buy Uncle Les some ear plugs if you take him for a drive
Cheers