no flux or tig. ha i used my mig. the welds are strong just not stainless. and actually if you have stainless wire you can weld stainless and the welds wont rust like regular wire. but stainless wire is pricey. some guy payed me like $20 plus a spool of stainless wire to weld fittings on to his kegs for his brewing set up.
Metal is going to get heat soaked. you would have been better with a plastic housing.
You know this has been my reasoning for not doing something like this, does anybody make like sheets of ABS plastick that you could buy then say cut it out sand it the use Polyurathane Epoxy or something of that nature to bond it together and make your ow air boxes ? or something simular that woouldn't transfer the heat from the engine bay as much ?