If you don't have a huge budget, JDM ITR pistons (P73-00) or USDM B16A pistons (PR3) raise compression to around 11.3:1 when using a OEM head gasket. This is a good compression ratio if you daily drive your car and don't want to use higher than 91 octane.

Of course, you will need a lot of other mods (valvetrain, tuning, exhaust, etc) to make full use of the higher compression ratio.