Doug - The P-40 always had a supercharger, in its original Allison engined version, and the later Merlin (P-40F) form. The main problem with the P-40 were its performance at altitude (being designed more for ground attack and coastal defence). No-one supposed the USA would need to defend against high-altitude attack. US fighter design was a little behind European at that time (but they did catch up fast!), and there was no armour protection and no self-sealing fuel tanks. The original design had just two machine guns (later four, then six).

In British and Commonwealth service it performed very well as a ground attack aicraft in North Africa.