Lego3410

ok ive been researching like crazy on here and nasioc! and every after market website i could find. the problem im having is that my 2010 legacy 2.5i na needs a new cat! But that is harder then it sounds apparently i have to replace the headers right? thought i was going to be cheap and easy. but im having a problem finding an aftermarket header that willl give me some performance as well (high flow cat or either no cat). all i can find is an oem replacement. i would like to kill to birds with one stone. Does anyone have any suggestions? would it mess up my 02 sencor readings if i just gut the cat out? havent done that in ab 8yrs ago when i had a transam.