I was thinking of a V6 for my racing Panda project but something smaller and rev happy.
The Mitsubishi FTO engine is tiny and 200bhp from the shelf. You can even have a fancy sequential gearbox as they are nearly all auto's and import only they're dirt cheap. They also rust like Fiats around the rear subframe so plenty in breakers yards across the land.
...as I said earlier the Panda I know of has a rear subframe made of X-1/9 bits and Hawk Stratos bobs. The 1.8 Mazda V6 is torqueless all noise and hardly any action.