If you gut the pre cats I believe you will need a MIL Eliminators to get rid of the CEL.

http://search.ebay.com/MIL-ELIMINATORS_W0QQsosortpropertyZ1

OR Go to www.spmotorsports.com they have them about 60 bucks
They call them O2 Enhancers on the spmotorsports site.

www.martianrepair.com