By federal law(USA, not sure about Canada or elsewhere), it is illegal to Move or REmove a fuctional cat converter.
That being stated...lots of people do it.<img src=/images/forums/snitz/thumbup.gif width=25 height=18 border=0>
Cat converters provide some needed backpressure on N/A motors, they also do a great job of cleaning up the schmutz your engine puts out. They are usually not a huge restriction in the exhaust stream.
If you get headders and a full exhaust, change out the stock cat for a high flow unit of the same diameter tubing as the rest of the exhaust.
The stock tibby cat narrows down to 1.5 or 1.25 inside. Going to a high flow cat will also increase the noise that comes out your tailpipe, so unless you want a LOUD exhaust, plan on installing a resonator inline behind the cat.
<hr width=60% noshade size=1 align=left>Leave it to Random to Needlessly complicate things.