Seems like an odd comment, fuel injectors should handle the fuel types they are designed for, if the plastic is failing than it's a design flaw or manufacturing fault. As for the boost reference, either the injectors are a higher flow (in which case a re-tune would most likely be required) or higher pressure capacity but I'd rather think he's talking rubbish. When running boost you need to increase fuel pressure, if you don't you actually reduce the amount of fuel an injector can flow. I'm not sure what the LS3 factory fuel pressure was set at but as an example, a lot of common injectors are rated at 3 bar or 43 psi, that means there is a 43 psi differential between the inlet port and discharge nozzle in the injector, if you were to put that same injector in a blown motor that makes 43psi of boost pressure in the manifold you then end up in a situation where the boost pressure pushing back against the injector discharge nozzle is the same as the fuel pressure which means you have exactly 0 differential pressure across the injector which means you have 0 fuel flow. I know the LS1 motors ran a dead head fuel system (with the pressure reg at the tank) which is ok for a n/a motor but IMHO for a blown application a return style fuel system that is boost referenced 1:1 at the motor is much better as maintaining the correct fuel pressure differential across the injector is better and more consistent which makes tuning better/easier.