Looking at the prices of Focus RS' now fella, may as well just buy one. When I did it, they were priced what they are worth, so anything I spent on the black one was well under budget. Plus you have to consider the fact, that when you insure the car you will need to declare major modifications....being the engine, all ancilliaries and the styling. So it virtually costs the same as an RS to insure. But of course, depends how dodgy you are!!!
But if you're still determined, I'll PM you