a) Low-“impedance” = low electrical resistance = more energy flowed to open the injector = faster opening speed. The difference in speed used to be huge. c) Now the fastest high-impedance injectors are faster than the normal low-impedance even though they don’t use as much electrical power to work. d) Vehicle makers no longer worry about low-impedance because the circuits needed to control the injectors are more expensive. Very little development is being done on low-impedance injectors (except for direct injection which sprays directly into the combustion chamber). So, that explains why the lows are considered superior to the highs. But, that is a reputation that is getting less true every year, etc. These Genesis 1000cc (and the specific Bosch family that the solenoids came from) are SUPER fast. That’s why they allow for smooth tuning even though they are so big. Okay, and here is lesson number two: 1) Notice that I said that the low-impedance injectors have faster opening speeds. That’s because they have stronger solenoids. These take that extra electricity to work properly. 2) They also have faster closing speeds because there is a stronger/heavier “return” spring that acts against the solenoid. 3) The return spring does not change in strength because it is purely mechanical. 4) By adding resistors to the low-impedance injector you increase the resistance. 5) At this point you will have converted low-impedance to high-impedance. (Again “impedance” = resistance which blocks electrical energy.) 6) Now, you will have a weakened solenoid but a super-strong return spring. 7) The result is much slower opening time (but no change to the closing time). In short… adding resistors to low-impedance injectors makes NO SENSE! J You will get much better performance out of a high-impedance injector that has a proper balance between opening and closing strength. I hope all that is easy to understand!