turbo sizing question

[1dollardog]

Ok this is for another project that I'm thinking about. Someone school me on turbo sizing. I am looking at a turbo that has a turbine a/r of .48 and a compressor a/r of .42 . Someone tell me how this relates to the size of a stock GN turbo. For example, much smaller, a little smaller, same size etc. Looking at this particular one for a small liter 4cyl project and don't won't to put too much punch to it.
Thanks