Not at all really. They just have a large diameter shaft/plastic nut on the back-like TM says-you might need to fabricate a backing plate of some sort, more so for the fronts.
Saying that the fronts were easy to replace. I had high level cans on mine so I fitted the backs in the tail pod by drilling it. The only issue with that is a) you've got a tail pod with holes in it should you ever want to change back

b) you need to make sure the rear of the indicators don't foul on the subframe when fitted. The indicator housings are quite long and the wires need room to exit without catching. The other option for the back is integrated indicators in the brake light housing should you not want the mahoosive fecking things Honda fit
Mine worked fine. Had no trouble at MOT time either...However, mini LED/micro LED's are much brighter and more visible to other drivers
The choice is yours
