The small turbo won't make any more power that 300bhp, even with a hybrid turbo (on the standard management and injectors etc). To go beyond that needs lots of hardware changes.

The large turbo can make 340bhp on the standard turbo with a set of greens, a 3 bar MAP sensor, stainless-steel exhaust, -31 actuator, EPROM and board, and uprated fuel pump.