"bolting on" a turbo to a totaly standard engine will result in a catastrophic meltdown of a pinston and ultimately complelely fuck the enging up.

getting a "rebore" isnt a simple process, your gonna need all new pintons to match the new bore, possbly new con rods for the new pistons, all of this involving a complete engine strip down and rebuild which always means £££

so tell your mate to stop talking shit please.