I have been using the diffusors in my secondary holes with no problems. That's with 1600cc injectors on E85 with pre turbo water injection. I have done hundreds of passes. They are still intact. EV14 is not magically better than 1990 Denss they are just cheaper to manufacture and new. If yours are cracked buy new ones if its possible to install them.

 

The issue lies in that they are ridiculously expensive tiny pieces of plastic that can become brittle and break into your engine. That's why I am seeking a good alternative if possible.

 

i had 1 good secondary one and found another good used one for $15 from a mazda mechanic. i have a whole pile of various primary injector diffusors. its not that dear. 2% extra fuel consumption over 1yr probably pays for them