After reviewing way too many threads and posts on this topic, I still find myself torn on how to proceed with installing my Euro headers. I'm aware that a few folks haven't had the best success with the relocation (messed up secondary cats) and that's not something I really want to risk.
Typical options Find a Euro Cat (almost as rare as a unicorn).
Modify the stock US secondary cats. Irreversible, and no guarantee that it will turn out like Pal's install some shop isn't going to do a hack up the cat and leave you with a expensive mess. Seems like if you find a great shop, and do not cut into the wires (expand wires) this seems seems to work fine (but still irreversibly modifies the cat).
What about other options such as:
Add O2 and EGT to the Euro headers themselves in exactly the same spot as the US stock headers. This would leave a set of unmodified stock headers if needed plus a stock secondary cat. Fabspeed and others have both O2s and EGT on the headers themselves (just like stock). With a tune, CEL can be eliminated. (Seems there's a debate on whether the Evolve tune returns a "readiness" code or not though.)
Disconnect the secondary O2s (and keep as spares), and use a tune to eliminate the CEL and provide a "readiness" code. I'm not sure if this is doable. If it were, this would require no modification of the Euro headers, and use a tune to avoid the CEL.
Thoughts? Comments?