A 2.5L car (97-99) only has one set of cats (in the mid-pipe) and one set of O2 sensors. The cats can be removed using test pipes and the test pipe should have a bung to mount the O2 sensors. The car will pollute more without the cat's but you shouldn't get any CEL's.
Here is a photo from engine back: On the left of the photo is the stock exhaust manifold, stock mid-pipe with the cat, and the Top Speed Pro 1 muffler. On the right of the photo is the stock exhaust manifold, cat delete pipes with O2 sensor, and Top Speed Pro 1 muffler.
Removing the cat's definitely increases the sound level. With no cat's and the Top Speed muffler, I wear earplugs. With no cat's and the stock muffler, the car is louder but might be livable. Everyone's noise preference/tolerance is different so its hard to say if this will be acceptable. YMMV.
