We installed a B20B in my sons 97 Civic and everything was perfect until he added an after market exhaust header. Now we can't get the header to stop leaking from the maninfold. The thick paper gasket that the header came with only lasted about a week so we installed a stock metal gasket and it still leaks. All the bolts are torqued to spec. Any ideas?

Thanks

 

check the gasket.

 

sounds like a cheap assed shitty header, its very possible the flange is warped.