Hold on there buddy....
From what I understand, The CEL comes on because the OEM setup has two O2 sensors at the end of the headers, one before the cat and one after. The Maxspeed headers only have a bung for one 02 sensor each. So, now you have one O2 sensor on each side that is "inoperative" or not receiving any reading and that will throw a CEL.
According to Maxspeed the permanent fix is:
"....you will need to relocate the 2nd O2 sensor right after the 2nd set of cats that also involves extending the wiring on the O2 sensors. This is the permanent solution. We can help you with this solution just ask we have the O2 weld sensor bungs to relocate."
This sounds like a good fix to me