here in illinois the sniffer test is a rather simple one for obd II cars. they just hook up the scanner to the computer and make sure all of the emission sensors are working as they should. right now- i have a shorty header and a random technology cat (which i believe to be going bad). i am pondering getting the 4-2-1 header and a mil eliminator. will i still be able to pass that kind of sniffer test? from what i read- it keeps the CEL from coming on and makes the computer/sensor read as though everything is fine- is this the case?