18" Blade's would just be the icing on the cake, but I have been quoted near £2000 for a set. I wish I had ordered them with the car, would have only been £850
A spoiler on the rear doesn't do anything for me. Having owned a Subaru Impreza with a huge ironing board of a spoiler on the boot lid, I think that cured me of the need for them.
Anyhow, the rear end of the Civic is fussy enough without additional ironing boards as far as I am concerned.