This is the same as the effect you get with a blown indicator bulb I suspect, ie. a reduced load causing the flasher relay to speed up, so my suggestion would be switch the relay for one from an earlier car without the bumper lights.
or wire in a 6.8ohm 25watt resistor in series
A cheaper alternative to the flasher relay; but why have a resistor heating up behind a panel and burning energy that could be going to the battery?or wire in a 6.8ohm 25watt resistor in series
A cheaper alternative to the flasher relay; but why have a resistor heating up behind a panel and burning energy that could be going to the battery?