emissions limits your options. gas avail. limits your options. budget limits your options. abilities also limit your options.
what power do you want? what gas can you afford? how thorough of a build(complete STi interior/HVAC/wiring/suspension/x-members/etc.?)
i would stay USDM @ this point in time. and since your going lightweight GC style, i would buy a wrecked WRX TR or something with the 2.5 thats not an STi(for cost limitations) but has decent brakes and no R180(unless you get a totalled car cheap) to convert to.
just some ramblings...