? about adding catted Y-pipe
JasonG
If that's the case, the pcm will think there's a little more air than there really is, and it may run a little richer because it's adding fuel for air that's not really there. Shouldn't hurt anything. Better to run a little rich than to run a little lean.
An SD tune is more sensitive to VE changes than a regular MAF tune. So with a MAF, the difference might not even be noticeable.
If Cat overtemp was turned off, you may need to get that turned on again. Some people say with a high flow cat it doesn't matter. I don't know.
JasonG

