I need to replace my cataylic converters 2008 ex 35 what to buy

If it's a Cali car you won't have many choices, I think AP/Eastern (Eastern Catalytic) is the only aftermarket for CARB compliant units. AP/Eastern is a good brand in general and my customers have had good luck with them. If you go with the cheapest out, expect to possibly need spacers added to the rear O2's to avoid P0420/P0430's. Bargain basement cats are often weaker than OE's and can cause low-efficiency codes even when brand new.