Background:vehicles in question are the 2000-2005 Celica GT (1ZZ-FED) This is from my personal experience/observation. The pictures linked don't show the difference clearly but there is a obvious difference between the pin hole spacing when compared side by side. Green Injectors: 250cc/min Pin holes very closely spaced, only clean ones ever found were the updated ones. The older version used in 00-01 Celica GT & 00-02 Corolla were almost always clogged up, 10 different vehicles, personally or family owned. And they all would set a CEL for fuel pressure, upon cleaning from RC Engineering located in California, the CEL would never come back and vehicle operated significantly better in both performance and mileage. The updated version used in the 02-05 Celica GT & both 03 Corolla & Matrix & some 03-05 Vibes (no idea why the discrepancy). These have never been clogged up (5 Different Vehicles), no idea why, they almost look identical, maybe a better filter located inside? Look updated based on the external looks which are identical to the NEW Denso Fuel Injectors being sold for all compatible models. Blue Injectors: 255cc/min Pin holes more widely spaced compared to the green injectors, like the updated green injectors, these I have never found to be clogged either. These are used in the 04-08 Corolla/Matrix/Vibe I have used four different sets of fuel injectors on my black 01 celica gt. 1) 1 set of the older green version cleaned by RC Engineering back to OEM spec of 250cc/min 2) 2 sets of the updated green version. Each time a used set was installed without any info on the flow, Redline SI-1 Fuel Injector Cleaner was used with a full tank of gas, and 2 subsequent full tanks of gas. The performance and mileage was consistent with the cleaned set of older green version. 3) 1 set of used blue injectors being used currently on the vehicle with a Redline SI-1 Fuel Injector cleaner. The performance and mileage are better with these injectors, the acceleration is a "tad bit" more responsive, and now when the "winter" gas is being implemented, I'm getting +2 mpg(3 different tanks so far) on regular driving. I got the same mileage (1 tank only) compared to the green injectors "regular" driving style with "pedal to the metal" driving style on these blue injectors. Confusion/Question is it possible the blue injectors with only an increase of +5cc/min compared to the green version, are better? is it because they have a more widely spaced orientation? why am I doing all of this? I like to constantly experiment different variations on my vehicles. And I want to see if I can benefit using the blue injectors on all my 1zz-fe engines. Related to why I'm doing this I have learned on these engines, using a valve clearance spec on both intake & exhaust, that is towards the loser end of the spectrum, produces better "power" and mileage, I do not know why though. Maybe less restriction?