u/Bulky_Wing6450

So I found a pretty decent deal for a catted downpipe on marketplace, and am planning to check it out. What are things I should be on the lookout for before buying? Owner said he had it for 1k miles before they got into an accident and sold the car, but kept the after market bits.

So I currently have on a flow master cat back with a y pipe, and no other performance mods. What are all the things I can add or remove to make my car sound louder in general?
Edit: I do not want to get rid of cats so I don’t fail yearly emissions check up.