ok i have an update, i now have 3w of total bulb as fietsbob suggested and the systems works great, for about a minute and then starts to pulsate and flash.

any idea whats going on? i have the tail lights mounted to the brake caliper bolt


* edit * It was a blink bulb -.- with a 1 wire setup it seemed to cut the circuit with every blink and make the headlight pulse aswell.