Gotta weigh in on this since it is being discussed again. I echo the real world/video game comment posted above.
Nuts and bolts: I've read all 14 million pages of tuning discussions on this forum. Regardless of what anyone says about what should work or even what does work, I always side with CSLACR when it comes to tuning for one reason: Results. Pick the nastiest challenge that GT5 has to offer you. Whatever your personal demon race is, find a CSLACR tune for a car to run that race and run it again.
I saw the light when I was working on the Impreza challenge in the seasonals. Ran that race so much, I got 2 1000 tickets out of it without winning. Tried CSLACR's tune for the Impreza done specifically for Laguna Seca, and by the first corner, I knew I would win. Whether you like him, his views, politics, religion, etc. ad nauseum, his tunes work and thus his methodology works. As I say whenever I am asked about these topics or tuning in general: "Honestly, I don't know. All I can tell you is that I believe whatever CSLACR believes."