i was wondering can you hook up shorties to a y pipe. with stock cat, and by doing that will it be louder, and a bit more performance. i was looking at edelbrock shorties.

 

The stock cat is still going to restrict you. You probably won't see much out of the shorties at all.

 

Shorties are a direct bolt up to the stock y pipe. It's a minor improvement mostly better low end, little better scavenging of exhaust, but dropping the stock cat and muffler (if that's what you're running) should be done first to see those gains.