Book title

Hi, Can anyone help with a book title please. I have read somewhere within the last few weeks about a book which for one thing explains how to alter the sleeper spacing on Peco 'OO' gauge track among other things. Its on the lines of how to improve rtr models. I have hunted but cannot find the reference to this book even though I know I have seen it somewhere. Can anyone help please? Many thanks. regards Moggie.minor