Ok, so you have a BSA motorcycle that was built in 1950. Being somewhat of a historical buff, you wonder how to size one of the Brooklands-style exhaust systems to fit the era.
Well, this book is your salvation. Or, it was mine. The details of exhaust systems are provided with the scientific background. The sizing information is given as well as the design objectives. So, it can be properly built according to the best theory at the time.
Does anyone else care? I certainly hope so!
Automotive tinkerers - proceed with guidance!