First the Injection system on 3gen is NOT dependant on RPMs, The CP3 has 3 plunger type pistons that rotate at about have engine speed, So lets say that at 800 that means 400 at the CP3, let's demand more volume at that RPM speed than the CP3(s) can produce, sense the Pump is a piston type it will create waves or a pulse that the farther apart the more damaging they become ( more manipulations the more damaging),its call the hammering effect, also the injectors have a small ball that open and close on demand, when the waves or pulse Don't concise with this action it beats the body to death,Modded rail(s) will help to keep the waves at a minimum or close together. Their is no downside to properly modded rail(s) all owners will experience some type of performance increase.