The same fuel jet can work for several tune ups........you just adjust the fuel pressure. There is no set fuel pressure, nor is there a set jet spread that you HAVE to use. The right spread and the right pressure, is the one that makes the tune happy.
ya the kit makes since to buy. hell 3 sets of jets is 96 bucks. and its 150 for 10. even if i dont use all of them lol. in my mind id like to corse tune with the fuel jet and fine tune with the pressure. thats how i did my plates.