I have been back and forth on what size injectors to get for my setup I have a stock Lq9 with a 222/224 .566 .568 112LSA cam with 74mm front mount turbo with stock intake with 91 gas, my normal boost will be 8psi -12psi max?

 

60s should be just fine and are simple to tune, but might be a little close depending on fuel pump and pressure. 72s if you don't mind spending a little more. I wouldn't go much higher than that unless you have an excellent live tune. The 80+ Injectors have a tendency to need a little more fine tuning.

 

I will be running a single walbro 255 or 400 with factory fuel regulator return style

 

400 will overpower your stock regulator.

 

I have a walbro 450 stock lines with 60lb injectors. On about 15lb with meth and my injectors are maxed out at 1/4 throttle. I would go bigger.