NMS use a custom crank, rods and pistons into a relined Duratec block (IIRC) to bring it back down to 1600cc, they then extensively weld the head and re-machine it to achieve the desired flow along with larger valves etc, a custom NMS profile cam is ground by Newman with solid lifters, then it's manifolds and a suitable turbo, finally mapped by Karl.
I think last I spoke the cost was around £6000+