How can I tell if a part will pass emmisions?

[BilLster]

gt-40 and gt-40 p's are O-E heads no problems with emmisions if the visual inspector even would notice the diffrence. as for parts chris was right aboput the manufacture to see if there is an exemtion # if the inspector gives you grief. we dont have air care here but in BC they do the sniffer test and when i was there i had to have a tire changed and the mech put my car on the sniffer to tell me how lucky i was to not have to pass and to his suprise my car was within the allowable margin. but i would of failed if he had done a visuale to back it up . diffrent places diffrent laws.