I use the regular unleaded (87). I don't have turbo so there's no use in using anything higher.
Using the "premium" unleaded with a higher octane rating doesn't give you any gains - it just means that the fuel burns at a higher temperature. In fact, it can even be damaging to your engine in the long run if you use an octane rating higher than what's recommended...plus it's money that could be spent on other things. (I.e. new exhaust, CAI, etc.)