Signal indicators

About installing non-original fender turn signal indicators, isn't it needed to change the T/S and hazzard flasher units?
8 bulbs instead of 6 can vary the flashing speed because increased resistance, no?
I would not think so, but you can use LED bulbs in the new turn signal indicators to reduce the load. As long as you have some incandescent bulbs the flashers will work properly with LED's. I did that on my Duster and it works fine.