Ok so my IS has the infamous p0420 cel code. I took it to my local shop that i get most of my work done and they told that the cat in bank 1 is in fact going bad and quoted me a price to fix it. My question is whether i should have them replace the cat with another oem cat or if i should look into doing something aftermarket. I you guys think i should go aftermarket what brands should i look into? and also if i do go aftermarket i would still like to be able to pass emissions...any help and thoughts would be appreciated. Thanks.