Bad fuel consumption
 

I just replaced my RX8 injectors with a set of Fiveo 850cc EV14. It idles well at 14.7 and runs well. It was tuned on the dyno after installation.
My problem is the fuel consumption is near double compared to my RX8 injectors. Is it a behavior of big injectors or is there something I am doing wrong?

Bad tuning.

Unless you have emissions to deal with you can be lean almost all over the vacuum part of the map. I had a car temporarily idling at 17.8:1 AFR the other day, I obviously had to richen it up because it was quite rough, but you get the point.

Also, make sure your wideband is properly calibrated, and if youre not sure its probably worth it to buy another sensor. Even if it turns out your sensor is fine, youll have a backup now.

THis brings up a point I have been meaning to ask...

Does this mean you can be higher than 14.7 for motorway or downhill cruise? i.e where you are just touching the throttle in between on the throttle and off the throttle.....

Mine sits at 17 - 19 at this point. Any partial throttle or full throttle is always 14 or less (11.5 ish as you get to WOT).....but that tip in point seems to be 17-19.

You can be very lean in cruise and decel (Higher than 14.7:1), but you will have to advance timing to keep it smooth.

size of injectors has nothing to do with fuel consumption unless you're running out of resolution to properly control them at small pulsewidths or they are crappy injectors OR pushing the car much harder/richer/etc.

post your map and logs.
your tuning needs work.