Just installed RollGuy’s EGR delete kit. His is basically the identical to all of the others, using the original exhaust clamp to affix a “cap” where the EGR valve would usually sit on the header. The cap is certainly centered, clamp tight. I even sprayed the cap with some copper gasket to aid in sealing. Still leaks a little. Can’t hear a massive leak, but it bubbles big time with soapy water.

Any ideas??? I’d like to avoid removing the header again and welding it shut.

Perhaps slap some of exhaust sealing goop on the cap and try again? As this is a header, I’m sure it sees more heat and pressure than stuff downstream where that hoop is traditionally used