How long would they last?

Take an old set of crushed headers and cut all pipes off at 2" of flange. Get yourself 4 pieces of 1 5/8 X 30 flex pipe. Weld all on and start snaking them any way you can to the old collector that was trimmed at the 4 tubes. Get everything snaked and reconnected, weld a brace from the collector to a bolt on bracket and then wrap the entire thing in stainless or asbestos header wrap. Would it last for a season? Just for fun.." bench racing", no plans....