It's only a car, as nice as I think the zed is, replace it if you're not having fun and getting upset over the running costs for the perceived performance you are receiving (there aren't many N/A V6 cars from 10 years ago pushing 280+bhp).
I used to have a kpro'd civic myself and wouldn't go back, even if it was quick it certainly does not make the noise the zed does.
As to the running costs of the zed? Insurance is a nudge over £500, fuel isn't THAT bad and tax is fine? Servicing is no dearer than any other performance car really. Don't drive like mad max and tyre wear shoud be fine too?