it depends. The one u have with that spec, will give a nice wide power band, and make a very fast road car. You prob have the ultimate spec for a driveable road car with power.

You can goto a stage 3 turbo - which is same as urs but with a 0.48 housing, not the std 0.36.

U won't have any real power below 3500 though with a 48, but it will be very strong once above that, and rev to 7k.