Replaced all 6 injectors, now leak test still fails

[Husky05]

Hello all, I recently replaced all 6 injectors this summer, actually i did 2 in February or march, then did the rest 4 in the summer time. Engine is a 2006 ISX 450 CM870

Well now I'm having a weird rumble at upper rpms, more like big boy rumble when I'm under load from like 1300 rpm and up. I checked my valve clearance and it's all good, fresh oil, new fuel filters. Issue is still the same. So I decided to just run injector leak test. well front and rear bank shows bubbles in the water jug when i crank the engine over. I have not yet pin point which injector it is yet. So it's for sure 2 or more injectors.

I am wondering what could have caused 2 or more to fail so early, are the reman injectors well known to fail so early? I have at least about 80k miles on the first 2 replacement, and about 40-50k on the 4 replaced in the summer.

Could a leak in the fuel system other than the injectors cause air bubbles to come out in the water test?