A T3/T4 seems to have become the sandard setup for a streetable turbo car. That would probably be your best bet. Because it is so popular already thats going to make it easier to tune your car because youll have more resources. Just make sure you sit down with someone who is about as close to an expert as you can find. Keep in mind that with a turbo youll get a lot more power but youre also adding a lot more moving parts into the equation which means more stuff to go wrong. As long as you dont cut corners and do everything right the first time youll be totally happy with the results.