Originally Posted by PoorMans180SX

The thing is, if you have big differences in turbine and compressor size, you lose turbine effeciency because the tip speeds are different, and power and transient response are sacrificed. Garrett has finally caught on with their new GTX3576. It's a GTX3076 compressor wheel with a 3582 turbine wheel. Spools exactly the same as a X3076 and makes somewhere around 50whp more.

Check out this article:

Turbo Tech: Compressor and Turbine Map Details

And this:

http://forums.evolutionm.net/evo-dyn...-gtx3576r.html