no worries, to be fair putting an rs turbo engine in is most likely the easiest way. but it does have its downsides like sometimes the cvh engine isn't too reliable. as where the zetec is!! plus you will have to change alot for the setup as well, in a sense you're better off buying an rs turbo fiesta and start from there lol.
some people do budget turbo engines and some can get it as low as £1000 the most of that cost is the turbo and management then they would use a decompression plate but again reliability with a decomp plate has been an issue! heres a good site:
www.zetec-turbo.co.ukthey show you how it can be done to get a nice 200bhp