What are the pros and cons to a Group N exhaust for my 197?

So my next purchase will be an exhaust for my 197, but I don't know where to look and what for as I want a group N exhaust and any info on it all. The main thing is what are the cons as i can imagine theres going to be a few but hoping theres none aha

So yeah just some info like prices and place to get one down etc..

Thanks Guys