Exhaust diameter needed for turbo?

[meerkatmag]

I have a 2.5 diesel NA engine that I've fitted a turbo and intercooler. I still have the original exhaust which is 2inch. Do people think this is ok or does it need a bigger pipe? The MK5 turbo has 2.5inch I think. It's all working fine but I don't think I have all the power yet and the exhaust is very prone to leaking fumes so maybe running pretty high pressure.