For the Type R. Yes, the stock ones are platinum and last about 80k kms. However the non type r, doesn't use platinum as standard, and lasts about 40l - 50k; according to the log book.

I know this, because the log book has two separate section for spark plugs. One for type r, and non type r.

I know for a fact, that there are platinum plugs available for DC2/DC4. Even though platinum isn't required. However I'm not sure if there is a platinum option available for the DC5 non type r. Unless Type R spark plugs can be used in the non type r (K20A3).