I tried this fix putting my header on yesterday and I am pulling an DTC P0420 catalyst below effiecieny threshold. Did some searching and found this same fix in other forums saying this should take care of it.
The only thing I think might have been done wrong is my choice of drill bit the size had been worn off on it so I don't know exactly what it is but putting a 1/2" wrnech over it there was just a little gap but not much at all and it's the biggest bit I have so next weekend I'll go buy a actual 1/2" bit to see if it takes care of the DTC.
But with as close as the bit is to the 1/2" wrench shouldn't it still work?
2007 zx3 f2 cold air intake,f2 header, flex-back 2.5 inch exhaust with Aero Muffler and 26" resonator
Last of the Hatches#86
Team Duratec #180