As posted earlier, the 10A is simply a rating and will not affect the flasher speed. The speed of the flasher is based on current draw of the entire circuit (wire plus lamp current draw). The relay is simply allowing a means to switch current paths but does not add significant current draw. Overkill...yes, will it work yes, will it affect the speed of the flasher, no. Hope this helps..Oh..and fyi
, I am a sparky. I've been an EE since '77.