I think I have seen your car before. 9000 aero in Hemel. My CS was actually bought off a mate of mine, you probably know them on Barnacres Road they used to have a 99, 2 x 900 and 2 x 9000 a ce and a black aero(Nice).
You might be able to fit a turbo engine, but you'd need the electronic boxes to drive it too, the DI/APC and the LH injection box. It would really be a good idea to fit the gearbox as well, as yours will be very low-geared for a turbo. Two-Stroke To Turbo in Hatfield have done conversions like that, although I don't know how cheap they'd be.
It's not the white CS that's recently appeared in Woodhall Farm not far from the roundabout, is it?