Intercooler piping question

what is the rec. intercooler piping size. 2.25 ?

If bigger piping is used lets say 2.5" - 2.75" will affect flow and boost producing lots of lag?

This is using a compressor A/R of .53

also what if you used different sizes before and aft the intercooler.

http://www.g2ic.com/forums/showthread.php?t=80937