Well, Pretty much cutting the CF to its size. Not much to it. Only issue you might find is that some the hubs will poke through the center bore, which you can't use flat piece you cut out.. My wheel spacers helped with that issue.
Anyhow, I drove the car around town yesterday (after fab'd a IC pipe from spare pipings I had) and the car felt GREAT!! It might be all mental since I haven't driven the car in like 2 months, but car felt more responsive and also coolant temp was ROCK solid!!! I never saw above 85C.. which normally I see 86-87 (even with the fan to come on at 86C).
Here are few pics from yesterday..