Good luck with the new bike.
I also wore a pair of work gloves, 3m quality painters dust mask and used eye protection.

The first 15 minutes will be nerve racking if you are nervous, the CAT is amazingly thin, lite and strong material and also sharp once you break it apart. So in those first 15 minutes you will get used to the drill bit biting and grabbing and jerking around the drill.
After that, piece of cake.
All I posted I just learned from others in the forums but Im the first I know to have used an extension (instead of a long drill bit)and finish up the job with the 1.5 inch bit. I think this is key.
The extension, rather then just a long drill bit allows some flex in the bit so you can dig down deeper along the bottom of the pipe. Anyway, I was thrilled the way it all turned out, I was also amazing the Bosch extension held those drill bits without breaking or giving up with all the abuse they took.

 

I don't understand how you could get the entire cat out this way. I can see removing maybe 70%, but how do you get the lower section, closest to the rear pipe out considering the drill bit can not bend around to reach it?

 

alarmdoug,
I drilled mine out this past Saturday, used the same extension and bits as you. Thanks for posting it up, it worked like a charm!

Zigzag,
The cat is composed of ceramic mesh, kinda like a cardboard box type construction if you've ever cut a box and looked at the end of it. That's the best way I know to describe it.

After you drill through the middle of it and get to the end of it, you'll have enough movement available to start moving the drill around to each side a bit to start chewing out the cat from the center out. Just keep the drill at full speed, but going slow with your movement to keep it from biting and jamming and it'll just fall apart. Just keep going with the drill, keep moving it around until you feel no resistance anywhere.

To answer your question, the 1 1/2" bit is big enough and you have enough movement to chew out that bottom back corner enough to get it to where when you fire up the bike to blow out the remaining chunks it'll shoot it out the pipe. After I fired it up and gave a few revs (LOUD BTW), mine was clean a whistle. Oh and be prepared when you fire it up, it'll blow "cat dust" and little chunks all over the place, lol.