You can also check the cat conv. with a infared temp gun if you have one or can borrow one from someone. You have to wait until the engine is at opperating temperature and then check the temp right before and after the cat. It should read cooler on the inlet side and hotter on the outlet. If it is the same then the converter is not working but is not clogged either. If it is higher on the inlet side and lower on the outlet side then it is clogged.