I figured it's about time I share this project with everyone on this site. I've been tinkering with this since November of '08 and it's finally almost complete.
Cliff notes on function: Two turbos are used, one smaller than the other. The smaller turbo get exhaust first in the stream, and the smaller compressor receives compressed air from the larger turbo's compressor. Being that pressure ratios multiple, this type of set-up can yield a large amount of dense air very quickly. Translation = lots of boost and very quick spool. Another huge advantage to this type of set-up is that it's capable of running more boost than any single turbo. This is how tractor pulling guys achieve 200 psi boost.
For a more detailed explanation of it's function, read this article:
Diesel Power Source - Articles - Turbos/Twin Turbos - Twin Turbos vs. Single Turbo
And for you visual people out there, here is a picture of a compound set-up on a Cummins diesel engine:
