It shouldn't be too hard. Take your time, you shouldn't have to worry about pieces getting stuck.
If you have a long prybar or crowbar, you should be able to knock out any pieces in the pipe.
If to have it completely off of the car, you can lay a piece of wood down and bang the whole thing on it, that should dislodge any pieces.

Did DIY for gutting the CAT problems
 

I followed the steps and it worked great, until I accidently stumbled upon a new problem. When I shut my car off now it won't restart until at least 30 minutes later, any idea what the new issue could be ? Once I let it sit it starts with no problem and runs great even idles on it own, but this is an issue because I turned it off to get gas and was at the gas station for 30 minutes. From now on I'll just leave it running when I get gas and put up with the dirty looks from people until I find the solution.

Not good.
That's the classic symptom of a dying engine, hot start issues.
Get a rotary specific compression test to be sure.

help
 

Bought rx8. Running and idling rough.replaced maf plugs and coils. It was only running on 2. After coil replacment started and ran better. Bunch of black soot coming out of tail pipe so i took it out for an hour of redline driving. Ran much better brought it home and shut it off now it wont start hot or cold. Im thinking cat is clogged. When i try and start it trys to start but jerks the whole car left and right? Was in process of pulling cat but its cold tonight so i called it day. Any thoughts. If the cat was fully clogged would it cause this?

Regardless im going to do this cat to staright pipe diy i only need safety where i live anyway

I've never heard of a bad cat causing that.
It doesn't mean it isn't, but that would be new to me.
It sounds to me like an engine problem.
I hope I'm wrong.
If you were driving it at redline for an hour with a clogged cat, that's not good.
Hopefully, it's just a clogged cat and you have broken motor mounts.
Be sure to update us when you discover what's wrong.
Good luck!

Having trouble removing the 2 brackets undernearth my cat. Tried penetrating oil, heat and drilling through the bolts with no luck. Would it be okay if I just cut them off?

A clogged cat will burn new coils

Yes, but the whole car shaking is usually not a symptom of a clogged cat or bad coils.

Why so many cat issues with these cars?
What's the best prevention?

people are lazy and not informed. failing ignition leads to clogged cats which kills motors. maintain your car properly and you will have much better luck with it. that being said, no rotary should ever have a cat

Say 200, what are cats good for?

:)

cats are good for chinese food and coyote bait and thats it