My Check Engine Light is on after a high flow cat and cat back system

[16v vw]

so i was getting bored with my 1MZ engine and brought it over the my specialist and he put my 2 1/4 magnaflow high flow cat on and a 2 1/4 cat back magnaflow system with a resonator and now my check engine light is on

o2 not within parameters "too much flow"

what should i do? any resistors that i can trick it with or how far should the o2 be moved? space the o2 with a non fouler? somebody told me to take the EGR off the car. i think that would make more CEL codes.

thanks in advance