[eschaider]

You have a virtual certainty of an air leak, that an O2 sensor will pick up, with slip fit headers. Everything on the exhaust side of an EFI fueled engine has to be locked up tighter than a bug in a rug. That means welded joints, thick flanges, gasket surfaces that are machined flat and good gaskets wherever a flange is used.

Of course you don't have to do this. You could use slip fit components and chase your O2 tail until you surrender and then weld up everything like you should have done the first time, You will save yourself a lot of anguish, work and pain by just welding it all up out of the gate.

There is a reason most exhaust shops are not good tuning information sources. It has a lot to do with the fact they don't tune, they build exhaust headers. The guys who build a lot of exhaust headers for EFI fueled engines will know not to use slip fit components if for no other reason than from customer complaints.


Ed