Not sure how strict emissions are where you live. I live in northern va which I consider fairly strict and I don't expect to have to swap my DP (cobb catted) out for emissions testing--could be wrong tho.
Also, people driving behind you won't have to smell your car if you stick with a cat. If you plan on doing a full exhaust as well, cops will notice both the sound and the smell. Unwanted attention if you as me.