Not just 8 tested nozzles. Guy takes in your injectors, the tips are enlarged to your specs, tested to be sure they flow equal, then re-installled on your injector bodies, the entire injector is then tested at 26,000 PSI and real world PW values. If they don't flow correctly the shop he works with can actual do calibrating on the injector itself. When you get them back you will know that all 8 flow within a very close percentage of each other as an assembly, not just that the tips flow equally.