Do what you can to try and use the search feature for the forums.
This 'mod' is for when you need to read more boost. The sensor is only responsible for telling the ECU how much air, in terms of pressure, the turbo is producing. When you mod your car enough with a turbo that is going to have sufficient pressure, that sensor will up the limit at what you ECU will see, thus giving your turner a better look at the pressure your turbo is producing.
Thanks for the sarcastic search results but they did not explain what I wanted answered. I had already read that thread thanks. Actually Digital Corpus gave me exactly the explanation that I was searching for.
I forgot to thank him in my previous sarcastic post.