I was wondering what the real difference is between shorties and LT headers because apparently i have been misunderstanding.

I thought shorties went from manifold to like a downpipe which would feed to a cat and then back.

I thought Long Tubes went from manifold, acted as the downpipe, connected to the cat and then back.

If this is true how come people talk about the cat being moved back with lt headers? If the cat is moved back with LT headers, do you need an exact catback that is made for this new cat location?

If I have to stay rather exact emissions legal, is it best to get shorties and high flow cat and catback? Whats the best high flow cat?

Thanks, hope you can clear up this seemingly basic question for me

 

any one?