you don't need a relay, you need resistors. they go inline with the wiring to the LED indicator. Traditional bulbs draw more current then LEDs, the relay for the lights it set to sense the current draw of two traditional bulbs per side(ie left and right turn signals) when one traditional bulb burns out or breaks there is less current draw and the blinkers flash faster to let you know that. Well since LEDs draw less current the relay thinks one of your bulbs is dead and flashes faster. Unless it really bugs you or you've had Police "tell" you to fix it, i wouldn't worry about the faster flash rate, the way i see it it just makes you a little more visible to those 4 wheeled boxes they call cars. Cheers 
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check these out on ebay.co.uk