I've used injector clean & rebuild services (generally ultrasonic cleaning) and have found the process worthwhile. Haven't done any GDI injectors, just port injectors as far as gasoline engines go. I had one engine where I didn't think I could see an mpg or performance change, but the significantly improved patterns and flow balance across the engine's injector set was worth it to me.
I've also had diesel injectors cleaned & rebuilt this way for equipment. Also worthwhile.
I've also had diesel injectors cleaned & rebuilt this way for equipment. Also worthwhile.