Fitting 17's is only good for looks mate. There is a fair bit of work involved to fit them, more than just rolling of the arches and you lose your handling capabilites. I didn't know you could get 205/45/15 tyres and if you have I bet they are not cheap. You will never see 200hp on blues though mate or without a stage 2 chip. If you are wanting more boost then you need to start thinking about a steel bottom end or you will be throwing your rods out of the block lol. I am running 17psi on mine atm and I reckon its around 200-220 but I have got uprated pistons and rods to cope with it. They say that the max standard bottom end can cope with is 16/17 psi but thats on a fresh engine. If you want big power though without spending an absolute fortune on the cvh is as above go full blown zetec turbo