I have a 07 accord v6 auto. I have the ATLP J-pipe and the greddy evo2 exhaust. If I want to install a hi-flow cat what diameters would I need and what brand would be best because I dont want to get a race pipe or resonator.
Just get Richie's test pipe. It's cheap, will bolt right on(took me like 15 minutes to replace with Magnaflow catback and Richie's J-pipe) and you don't have anything to worry about with replacing the third cat. There is no sensor; it's basically there so Honda can put a ULEV sticker on the car.