For anybody about to venture into the world of a rebuild, turbo change, intercooler change, or a general increase in power would benefit from understanding it's not just about whacking a bigger turbo on, or winding the boost up! There is a science to it, & here is are some pretty good links, full of information & equations.
http://www.gnttype.org/techarea/turbo/turboflow.html
Here is a simple calculator if you know your figures:
http://www.stealth316.com/2-turbotemp.htm
Intercooler sizing write up:
http://www.turboneticsinc.com/sites/default/files/AllAboutIntercooling.pdf
Hope these help.