Sorry for all the posts but does a SOHC non-vtec ZC have a mass air flow sensor???? If so isn't it suppost to be on the intake????? I was told that a faulty intake could cause high NOx readings......could an aftermarket air intake cause that....when the car is started it sucks in alot of air and u can hear it over the actual engine itself....maybe a stock air box and filter is needed.....does anyone have any info?????