You can convert car to 'old cossy' mansgement and I think people chrge from £1000 -£2000 depending on whether you change the turbo, and on the spec of the conversion. I would go bigger turbo then straight for Blues for around 380bhp.
Swapping straight over to std spec will make you slower, and going for greens and chip etc will only give you the sort of drive that you would get from a nicely set up chipped small turbo model!