In 40 years I’ve never seen such a scam. The labor book time for #5-7 passengers injector is a fraud! The allow 8.9 hrs. . They assume the tech must remove the whole side shielding and fuel rail. That is to not harm the fuel rail by flexing the injector end pipes. When in fact they only need flexed 3/4 if an inch to remove the injectors. So the last two on that side require removal of the inner fender, one bolt shield and two bolts one holding the fuel line one holding the injector in. A cave man could replace those injectors in 2 hrs. 2,000.00 labor ! Now the forward injectors 1-3 could be a different animal but the two rear are not 8.9hrs labor and all techs know it as do the GM dealers.