I installed load resistors when I changed my turn signal bulbs to LED to put the flash rate back to normal.
www.superbrightleds.com

50W LED Load Resistor Kit - 2 Pack
6 Ohm, 50 Watt load resistor kit. Solves common LED turn signal problems with hyperflashing and bulb out warning indicators. Connect one across each LED turn signal bulb to simulate filament Tail/Turn signal bulbs. View Installation Diagram & Instructions [PDF]. Mount the resistor away from...