I gutted my main cat about 2 years ago. Just make sure that it is actually your main cat that is clogged up. When you get the cat off, start the car to make sure it is not one of the precats that is clogged.
I gutted my main cat only to eventually find that one of my from precats were clogged. So I wasted two days instead of one. You can gut them pretty easily with a screwdriver and a hammer.
Also be careful that you don't break any bolts.
I have put another 60000 Km's on mine since I did this and have had no more problems.
