4 psi is impossible to stick with. Eventually, you will want to run more boost when you get a little boost happy. My first turbo integra, I was running 6 psi on stock internals because it was a DD. Now I am boosting 14.5 psi and loving every moment of it. It's all in the tune, which makes a difference how long your engine last. I have 310cc injectors for sale if your interested.