The holes are pretty big, and Saleen cuts out the underpadding to make room for the gauges and wiring and leaves it pretty ragged looking.
I replaced my 01 style (Boost/Intercooler Temp) style with the newer 03/04 pod (Boost, Intake air Temp.) and it did pretty well, although the newer one has a slighly smaller footprint.
Its a PIA.. but just take your time. The hole is massive though. When I took mine out, I had to take the center consol out and my instrument cluster...