I must disagree with 34-40 I was in the emissioms business sence the norris thermadore pcv law thats when I got my first licence in 1962 when we blocked the road draft tube and installed a primitive pcv valve and taught emissions for yesrs the purpose of air injector sys. is to add o2 down stream to continue to burn the unburned ( hc) hydrocarbons later years the added catalitic converters think of thoes as after burners they need o2 to work if you turn off the down stream o2 it won't be long before you plug op the cat. and you will have major drivabilty problems thanks to the advent of the onboard computer we have come to the point that we can controll the a/f mixture and timing so precise we can have cars that perform, get great fuel miliage, and are clean the newer cars when you put them on the infred red emissions tester they come up what we call owl eyes 00-hc 00-co- 00-o2 the air going in the intake is dirtier than that comes out the tail pipe