true, not required, but just like a good CAI mod, a tune is needed to get the most benefit from the mod
No tune required refers more to the CAT themselves functioning within OEM/EPA specs, so the downpipes will not throw CEL or codes which then make you fail emissions testing.
That also means that your tuner does not have to disable the CEL code for O2 sensors in their tune which of late has gotten a few of them into trouble with the EPA.