As I own a 3000GT, I know it's limitations. Naturally, owning a sporty-looking car, I want to back that up with actual power.
This book was fairly well written, offering several tips that will save you from detonation (which unless you like swapping motors, you'll really want to avoid that). My only complaint really is that the book is a bit thin (128 pages). It does contain a lot of information, and is well worth the price; but all in all, I wish there had been a little more weight to the book.
Nitrous does offer several benefits, and this book explains expected yield, supporting modifications (if you ever thought you could do a hard shot of nitrous on your stock, passenger car; you need to buy this book right this instant) and the hows and whys of nitrous. I thought this was an excellent book and I'm seriously considering adding a nitrous system to my vehicle after reading it.
I would suggest a turbo-charger if you're looking for "all the time" power, but if you're looking for a little extra "boost" off the line, n20 is your bag. This book tells you how to make it work for you.