Exhaust rattle / cat delete pipes cure?
 

My '02 S model has no noticeable exhaust rattle when it's cold, however as soon as it heats up it rattles terribly. It rattles when moving or just sitting still blipping the throttle, and is most noticeable on accel and decel. Of course I need to get it up in the air to check the heat shields (They're on the rear most cats, right?). Assuming it's the heat shields, the fix is easy. However, in searching, it's confusing to me what the issues normally is if it's an internal component rattle. If it turns out to be internal, is it usually the rear most cats? If it is I'm thinking I would just get test pipes and pull the cats out. What's the most reasonable place to buy these? Are there any check engine light issues with the test pipes in place?

Get under the car and verify.
In my case, one of the rear cat heat shields was buzzing/vibrating.
All better after silencing it with a worm drive hose clamp of the appropriate size.