Under our Product and Technology section we discussed the use of multi-stage turbocharging to achieve higher boost pressures. Compressor performance requirements consist of both higher pressure ratio and an effective operating area (i.e. compressor map width). In general, working within the limitations of current materials and product design can make significant improvements in one area at the expense of the other. Radical redesign to bring into production new concepts such as an upstream axial stage (a combined axial and radial compressor stage) or inlet guide vanes would all provide significant improvements in compressor performance. These solutions bring additional cost and complexity.