i have used the z1 ones for 5k-6k miles problem free...they are all ohm'd and flow tested...i would recommend them to some extent, i would never use them as permanent replacements but i needed something to hold me over till i could gather enough funds for a full upgrade on the injectors....plus bear in mind a brand new injector can fail within a few 1000 miles too because of electrical issues...u never know, best bet get one from classfieds since u only need one