l just installed an aftermarket exhaust (catback) which l believe to have taken off the second of two cats. l am wondering if installing an aftermarket header will delete the first cat? please answer if ur a knowledgable source, thanks :)

you can not remove the cats it will set a code ,

There is not 2 cats but 1 is a resinater and if you take off you will have all dash lights on and no way of shutting off and solving problem at same time. These cvars are carefully engineered and doing anything besaides factory aftermarket you will be voiding warranty and car will never run right. The engineering is why Toyota is so reliable and why a 280Hp toyota can be faster than same GM car Hp and weight and also perfoprm much longer.

yes, u will.

there r 2 catalytic converters, the main one which is in the header & the 2nd one is in the midpipe which is what u already removed for ur catback exhaust. adding ur own header will mess with ur O2 sensor so u will need to find a way to turn it off. l forgot, but there is a way to fool the ecu or the sensor (i forgot which) into thinking there is a cat so the check engine light turns off. check out clubsciontc.com or scionlife.com for help, as many people know how to fix that problem.