Ferrari Testarossa, and 512 Berlinetta Boxer, the flat 12 progression
Maybe I should take the time to get the 365 Berlinetta Boxer out of the depths of the basement to have a major spread of the horizontally opposed 12 cylinder Ferrari Street cars. This photo shows the 1979 512 BB, the last generation of BB, the 1984 BBI in red and the first generation Testarossa with the single mirror and knock-off wheels.
The Testarossa is definitely a major improvement on the Boxers because you can drive it with ease and comfort. The Boxers have an odd driving position and showcase the race car lineage of being difficult to drive unless you are at a high rate of speed.

Ferraris with horizontally opposed 12 cylinder engine