The problem I have had when modifying my car has been "at what point am I satisfied with the power". Its hard to know at what point, or hp, you will be satisfied with it as in the end you'll want more. And because you thought you'd be satisfied with the 320hp turbo, you'll find you will now have to sell it to buy the 450hp turbo, or the 550hp turbo and so it goes on. I'm not disagreeing with sydneykid, as I also believe you need to match as many parts to each other to get an overall excellent package, its just hard to know how much you want. I've got a turbo that will support 450-500hp, an intercooler that will support 500hp flow, but I find the turbo a little laggy and slow. I'm hoping with the new ecu and a HKS cam gear that will help the response. I may also look into the lightweight flywheel, lightweight pulleys (if anyone makes them) for better engine response and maybe some cams.