I'm guessing the 9K as quoted by PinkRinse (correct me if I'm wrong Ayesha) is for a supercharger installation which I take it goes in place of the A/C compressor and is driven by the accessories belt.

I would imagine a turbocharger solution to be cheaper. My dealer intended to fit a turbocharger on his JWRC replica car but he's not got arount to it yet. His project is frozen for the winter (ha ha, I like my choice of words). Nevertheless according to him you could get around 200 bhp with it blowing at only +0.3 bar (very little). I would also imagine that with a turbocharger you get to keep A/C.