I tapped mine into the number plate lights wire that runs on the driver side rear boot area.
I followed mateyguvs guide and had no error lights on dash, i tigersealed mine 3 times and they held on fine. Took them off after them being on for 7months and a bit of the Tiger seal started to come apart and resealed them again and just fitted them back on today. Seem stronger than before but time will tell.
Only minor issue i have is that when i have my lights on and i have the FM radio on, theres a small cracking noise.
More pics in my build thread. I think i have some pics of where i split it too. Ill see if i can upload
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