ive gone through 2 carsound cats on my jdm header because of the "honey comb" breaking. people say it is because i have an obd-II car and it tends not to last long.. which it didnt, my first carsound cat broke within 3weeks and the 2nd broke within a month and a half. stock cat wont fit. this pisses me off. right now, its basically a test pipe and im just planning ahead because i just moved to where there's emissions tests.