This book provides some good basic information for people new to tuning and forced induction. Plus it has lots of nice pictures.
However, the author quotes too much of his own opinions as if they were facts. As opposed to the Bosch automotive books, where no opinions are expressed, only technically backed data.
He often fails to take into account important factors and many things said in the book don't have anything to back them up.
When recommending fuels or boost levels he doesn't take into effect turbocharger size, engine revs and the application. (drag racing or rally/endurance/top speed?)
He also advocates slacky and even dangerous methods of building systems, and suggests engine management should be taken lightly (when the fact is, it is one of the most important things when dealing with fuel injected engines). No performance expert would ever consider turbocharging a petrol engine without retuning the ECU or installing an aftermarket system.
He also expresses his opinion on water injection systems, and states they don't have any application. This is so far from the truth, water spray is an excellent coolant when used in small amounts, where there's limited intercooling capacity or heat soak. It also keeps the combustion chamber clean.
Overall, not a bad book but I'd really not rely on it as the only deciding factor when building a turbocharged engine.