You guys aren't exactly helping poor alanmont
There have been a couple of posts about removing the cat. Basically, there are three ways -
1. The Brute Force approach (knock it out from inside the pipe with a screwdriver/big hammer, use a drill bit (spade bit) and a big hammer, use a long piece of pipe/steel rod and a big hammer or use an air chisel).
2. Cut out the section of pipe containing the cat and reweld a straight section in place of it.
3. Try and find a complete header assembly from a bike that came without the cat (Australian/Sth. African model).
#3 is the most elegant solution, but also probably the hardest to find.
Removing the cat lets you use the best tune available (one of the custom tunes) - but only if you also fit a better exhaust. The tunes are available in the "sticky" at the top of the Tuning section.