Depends whats in the kit. If its just basic and includes mani, downpipe and turbo with oil and water lines I doubt you'd see change from £1500 if not more but you need all the other parts to make it work ie. injectors, intake, 3inch maf, filter for the maf, engine mounts, intercooler connectors, fuel pump and thats assuming you already have an uprated intercooler and exhaust system. Even without the labour you could do £6k on parts turning a standard car into a big turbo one with good suspension, brakes, clutch, diff and everything else.