Ok, not sure if its because of the FMU or what...but ONE of the injector is leaking from my friends car. He has a 12:1 FMU. And has a 2.7 mm thicker headgasket boosting at 10 PSI on his gsr and the injector closes to the FPR is leaking from the top!

BTW, the one that is leaking, the green O ring that came with the injector was busted up so I used one off of the stock one and maybe the stock rubber o ring is smaller? Do I need to order some O rings from RC Engineering?

Or maybe I need to tighten the fuel rail a little bit more?

 

Since it's an o-ring seal, tightening the fuel rail down shouldn't matter - the RC o-rings are slightly off-size from the stock ones so I would suggest you get a replacement O-ring from RC.

 

You more then likely damaged the new o-ring when you reinstalled it and weakened it and is now leaking. Just use a OEM one and it will be fine. You do not need to get o-rings from RC. To prevent install damage make sure to oil up the o-rings before installing them into the rail. Install the injectors into the rail then proceed to mount and bolt down the rail.

 

Is it maybe that he has a 12:1 FMU? His fuel pressure is really high.

 

That certainly doesn't help, but there's something wrong with the o-ring if it's leaking.